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Raman scattering is sensitive to lattice order and effects such as implantation induced damage, encapsulation and annealing associated strains, and polycrystallite formation can result in significant changes in the spectrum. Semi-insulating (100) InP and GaAs substrates were implanted with Be or Si and the laser-induced Raman spectra were measured as a function of implant fluence and annealing. Results and discussions on the variations of the LO mode intensity and the appearance of a well-defined signal at the TO frequency are presented in this paper.

The stoichiometry and contamination of low temperature layers grown by the pyrolytic decomposition of silane in an ammonia‐ and oxygen‐rich atmosphere on and Si substrates are reported. The chemical composition and chemical bonding properties of the films have been analyzed by Auger, nuclear reaction analysis, optical, Rutherford backscattering, and SIMS techniques. Capacitors were fabricated on Si and substrates, and the electrical characteristics were measured. The layers exhibited physical characteristics similar to those of thermally grown layers. Analysis of the films indicated a uniform distribution of Si and O throughout the films. The N concentration measured in the films ranged from 1 to 3% of the O concentration, depending on the growth parameters. The optical results indicated some evidence of small amounts of Si‒N and N‒H bonding. All films grown on Si substrates in the presence of or on substrates had In and Sb contamination throughout, with the In and Sb content increasing from the film/substrate interface to the surface.

Amorphous germanium films were implanted to high boron levels, ∼1021/cm3 peak concentrations. Before and after implantation the conductivity measurements fit the relation logσ∼T−1/4 and no evidence of intravalence absorption was observed indicating that the Fermi level was near the center of the band gap. Thermoelectric power measurements indicated that the samples were weakly n type before implantation and p type after implantation. The position of the fundamental absorption edge shifted to lower energy upon implantation and to higher energies upon subsequent anneals. Implanted recrystallized films were strongly p type, exhibited intravalence absorption, and had very low dc activation energies.

Semi-insulating chromium-doped GaAs was implanted with 100 keV Be ions to fluences of 5 × 1013 and 1 × 1015 ions/cm2. Specimens were annealed at 800°C for thirty minutes. Beryllium atomic concentration profiles, as determined by secondary ion mass spectrometry (SIMS), were compared to the defect density profiles obtained from transmission electron stereomicroscopy techniques for the annealed samples. A major redistribution of Be was observed compared to the as-implanted distribution after annealing at the higher fluence, whereas only a slight redistribution of Be occurred for the lower fluence. A major difference in the defect density profiles was observed with the fluences used for this study in the region where the annealed specimens were compared. The distribution of defects throughout the implanted-annealed layer was examined in GaAs annealed after implantation with the higher fluence using sectioned specimens. The relationships between the atomic Be concentration profile, the defect density profile, and the distribution of some specific defects were compared in these sectioned layers. The distribution and size of defects appear to be directly influenced by the Be concentration and its associated implantation induced damage.

The electrolyte electroreflectance (EER) spectra of AlxGa1−xAs have been obtained in the E0 and E1 regions and for Al concentrations ranging from x=0 to 0.65. From the spectra obtained under low field conditions, the variations of the interband energies with Al concentrations have been established. Following Aspnes [Surf. Sci. 37, 419 (1973)] we have made detailed analyses of the complex resonance line shapes of the experimentally observed modulated reflectance spectra. The parameters Γ and Eg have been calculated and these have been used to generate theoretically the spectra for comparison with experimental results. In addition, we have also examined the effects of dc bias on the EER spectra. Variations of E0, E0+Δ0, E1, and E1+Δ1 have been discussed and results on the line‐shape parameters have been presented.

Interband transition energies for AlxGa1−xAs layers grown by molecular‐beam epitaxy (MBE) techniques have been determined using the electrolyte electroreflectance (EER) technique. The observed data fit quadratic relations for E0, E0+Δ0, E1 and E1+Δ1 to describe variations of energy with composition. Although the x values were not accurately known, the internal consistency of the data is excellent. Given a single bowing parameter we show that accurate values of x can be determined. The EER technique can provide x values with an accuracy better than 0.02 and information on changes in x as small as 0.002. It is thus ideally suited for studying MBE materials.

Atomic depth distributions for the low atomic number ions 73Li, 94Be, and 115B implanted into channeled and random equivalent orientations in crystalline silicon have been studied. The atomic depth distributions were obtained by secondary ion mass spectrometry measurements on samples implanted to fluences low enough to preserve the integrity of the channeling components. All implants were performed at 150 keV into the 〈100〉 and 〈110〉 directions and into the (111) random equivalent orientation of float‐zoned (low‐oxygen) silicon crystals. The results show that in the three orientations studied the ion ranges decrease with increasing atomic number Z1. This is indicative of the strong increase in electronic stopping Se for the Z1=3, 4, 5 sequence. The increase in ion penetration in the channeling orientation is greater with decreasing Z1 in the lower electronic stopping 〈110〉 channel than in the higher electronic stopping 〈100〉. Values of Se determined for channeled Li and Be at an ion velocity of 1.5×108 cm...

Ultraviolet radiation should be useful for the elemental analysis of materials, similar to the numerous applications of visible light and X-rays. In this work, exploratory spectral measurements in the 1000–3000 A region were made using noble-gas ion impact to excite elemental and compound targets. Lines, mostly from neutral or singly ionized target atoms, were identified. Strong lines potentially useful for elemental analysis are tabulated.

Atomic profiles of ion-implanted Be and S in GaAs have been measured as a function of implant fluence and annealing temperature. Concentration versus depth profiles were ob-tained by means of secondary ion mass spectrometry (SIMS) techniques. Pyrolytically deposited and sputter-coated Si02 and Si3N4 films were used as encapsulants for the 500 to 900° annealing study. Semi-insulating GaAs was implanted with 200 keV34S+ to fluences of 1 × 1014 and 52× 1014/cm2, and 100 keV9Be+ in the 1 × 1013 to 1 × 1015/cm2 fluence range. The S profiles did not change significantly after annealing at 800°C, although there was some skewing after annealing above 600°C. In contrast, the Be profiles showed significant changes and a decrease in the peak concentration for the ≥ 5 × 10T4/cm2 implants after a 700°C anneal. After a 800°C anneal the Be profile was essentially flat with a monotonic decrease from the surface into the implanted re-gion and a 900°C anneal caused a further decrease in the Be concentration. Profiles of Be implants of ≤ 1 × 1014/cm2 did not change significantly after annealing indicating that the higher fluence cases were related to solubility effects.

We have performed photoluminescence (PL) measurements on GaAs-Al0.3Ga0.7As superlattices where Si donors have been selectively doped at the center of the non-interacting quantum wells. A PL feature is shown to be donor related and is attributed to the radiative recombination of an electron of a neutral donor at the center of a quantum well with a heavy hole. Furthermore, our measurements indicate that the binding energy of the electron bound at a neutral donor is slightly larger than that of a coupled electron heavy hole exciton and, in addition, is significantly larger than that observed for donors in bulk GaAs. These observations are in substantial agreement with recent theoretical calculations.

The introduction of impurity atoms into a surface by means of ion implantation is a well established technique in the semiconductor field. The main advantages of ion-implantation doping are its high controllability, uniformity, and reproducibility. Increasing applications, coupled with the development and availability of commercial equipment, has resulted in the use of the implantation technology in most major semiconductor processing facilities. Discussed in this review paper are: the ion-implantation process; standard ionimplantation equipment and operating parameters; and applications in device structures.

Electron spin resonance (ESR), and 71 Ga and 75 As nuclear magnetic resonance (NMR) measurements have been performed on a 20μ thick film of a-GaAs deposited on a SiO 2 substrate by molecular beam epitaxy. The ESR spectrum exhibits the four-line S = 1 2 , I = 3 2 hyperfine pattern characteristic of the singly ionized arsenic antisite defect (As Ga ) commonly observed in crystalline GaAs. The concentration of As Ga centers is estimated to be 10 17 −10 18 cm −3 which is 2–3 orders of magnitude higher than those typically found in as-grown (unirradiated) crystalline samples. 71 Ga and 75 As NMR linewidths suggest substantial quadrupole broadening due to slight deviations from crystalline bonding parameters, but with overall preservation of short-range tetrahedral order.

A novel technique has been developed to produce n+"pockets" in semi-insulating GaAs bulk material. This technique has produced thick pockets of highly conducting epitaxial material on the substrate surface. The pockets were formed by the growth of a liquid-phase epitaxial (LPE) layer into holes which had been etched into the substrate. Surface uniformity was obtained by chemo-mechanically polishing the substrate surface under tightly controlled conditions. Polishing rates as low as 0.2 µm/min have been obtained. Photographs taken of the pocket cross-sectional area have revealed that growth occurred throughout the entire pocket region. Growth was even found to have occurred along the irregularly shape walls of the pockets. The continuous growth throughout the pockets coupled with the subsequent polishing of the substrate have produced exceptionally smooth and planar surfaces. Thicknesses as great as 10 µm have been obtained for the n+pockets using this technique. Mixer diodes have been fabricated onto these layers and tested. Preliminary dc measurements taken on these devices have yielded a zero-biased cutoff frequency (F co ) of 800 GHz with a series resistance (R s ) of 6 Ω and a zero-biased capacitance (C 0 ) of 30 fF.

Resonant Raman scattering experiments on GaAs(Si doped)-${\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$ quantum-well structures show transitions involving the ground state of the donors and narrow resonant donor states derived from higher conduction subbands. These new impurity-related features, which occur at slightly higher energies than the associated conduction intersubband excitations, have been studied as a function of power density, temperature, and well width.

Secondary ion mass spectrometry (SIMS) has been used with differential resistivity and Hall effect measurements to study the 900°C diffusion of implanted Be in GaAs. Some outdiffusion of Be into the Si3N4 encapsulant occurs for surface Be concentrations above 1 × 1018 cm−3. However, excellent agreement between the electrical and atomic profiles indicates that 85–100% of the Be remaining after annealing is electrically active. The concentration-dependent diffusion observed for implanted Be in GaAs was not significantly altered in experiments using hot substrate implants, two-step anneals, or annealing with Ga and As overpressure.

Chemisorptive luminescence, very similar to that seen by McCarroll [J. Chem. Phys. 50, 4758 (1969)] for oxygen on polycrystalline W, has been observed for oxygen on Si(111) surfaces. It is a diffuse gas‐phase emission extending 2–3 cm above the crystal surface; the spectrum appears continuous, in low resolution, throughout the visible. About 1 in 107 O2 adsorptions produces a photon; no emission is seen during chemisorption of NO, NO2, CO, CO2, and N2. The luminescence decays with hyperbolic kinetics; a model is proposed relating the hyperbolic dependence to the logarithmic rate of surface oxide growth.

Oxygen 18 adsorption on silicon activation analysis measurements used to obtain kinetic curve for chemisorption from monolayers

Coloration studies of alkali halide crystals have been extended by investigating the color centers produced in LiF by 3.0MeV 3 He, 40 Ar, 84 Kr, and 2.0MeV 129 Xe ions. From the F -center growth curves it has been determined that 666 eV and 1150 eV are expended per F -center created by the 3 He and 40 Ar ions respectively; the curves are linear up to approx 2.3 × 10 18 F cc and 2.4 × 10 18 F cc , respectively. The optical absorption spectra of the damage produced by the ions have been quantitatively resolved and compared to the damage produced by gamma rays by means of a least squares Gaussian curve fitting computer program. For the 40 Ar-, 84 Kr- and 129 Xe-irradiations the data are best fitted by the formation of 3 bands near 3.22, 2.97 and 2.22 eV and the 3 He data by a small band near 2.90 eV. Damage profile curves, obtained by etching, yield penetration depths which agree qualitatively with calculated values and show that the damage is fairly uniform.

Beryllium‐implanted liquid phase epitaxy n‐AlGaAs layers have exhibited p‐n junction behavior after annealing. Graded or abrupt junction behavior was found to be implant fluence dependent. Secondary ion mass spectrometry Be concentration profiles indicate that the graded junctions observed for the higher fluence implants were due to in‐depth migration of Be. Mesa diodes have shown ideality factors of about 2 and avalanche breakdown in reverse bias.

Auger spectroscopy has been used to measure the composition of ion milled GaAs surfaces in ordered and disordered states. Disorder was introduced into GaAs single crystals by implanting Se+ (5×1014/cm2, 100 keV) or Ar+ (5×1016/cm2, 20–100 KeV) ions. Auger composition profiles with 0.5 keV Ar+ ion milling exhibited As‐depleted layers that extended to approximately the depth of the implant region. An enhanced Ar concentration was also seen in the disordered region. These results are compared with similar composition changes in GaAs produced by low energy (

Photoluminescence spectra from ion‐implanted Be acceptors in GaAs have been studied as a function of wavelength and intensity of excitation light over the implant‐fluence range 3×1012 to 1×1015 cm−2. It is demonstrated that the nonuniform distributions of implantant concentration as a function of depth in the implanted layer produce a profiling effect which causes anomalous changes in photoluminescence line shapes and energy positions as a function of excitation intensity. These results imply photoexcited carrier diffusion lengths of much less than 1 μm in implanted and annealed layers in bulk GaAs.

Photoluminescence spectra from VPE GaAs implanted with overlapping distributions of Be acceptors and Se donors have been studied as a function of excitation intensity and temperature. Donor‐acceptor pair radiative recombination involving implanted acceptors and implanted donors has been observed for the first time and provides the first direct evidence for the optical activation of implanted donors in GaAs.

We report boron profiles as determined by secondary ion mass spectrometry that result from implantation into (100) silicon at (0.0±0.1) degrees through various thicknesses of thermally grown silicon dioxide. The implants were performed at room temperature at 150 keV to a fluence of 4.0×1013/cm2. The oxide surface layers examined were 7.6, 33.6, 101.5, or 140.0 nm thick as determined by ellipsometry. The boron profile for implantation through the 7.6‐nm oxide surface layer was only slightly degraded from that seen for accurately aligned implantations into bare (100)‐oriented silicon, while implantation through the three thicker oxides results in profiles similar to those obtained from random equivalent implantations into crystalline silicon. The systematics of the dechanneling of the implanted boron as a function of the thickness of the amorphous surface layer are analyzed and discussed.

Transitions involving donor states were observed in resonant Raman scattering experiments on Si-doped $\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}\ensuremath{-}{\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$ multiple quantum wells. The electronic scattering gradually transforms into photoluminescence as the exciting energy is tuned across the resonance. The largest contribution in the spectra is associated with $1S\ensuremath{\rightarrow}2S$ transitions of donors near the center of the wells. The experimental results show good agreement with recent calculations.

Differential resistivity and Hall effect measurements and secondary ion mass spectrometry (SIMS) are used to study the annealing behavior of GaAs doped with high Be concentrations during growth by molecular beam epitaxy (MBE). The diffusion coefficient of MBE‐grown Be in GaAs is determined to be (0.5–1) ×10−13 cm2/sec at 900 °C, a value which is two orders of magnitude lower than that for implanted Be of equal concentration [(2–3) ×1019 cm−3]. The concentration dependence of the diffusion of MBE‐grown Be in GaAs is also observed to be substantially less than that for implanted Be. The implantation of He in Be‐doped MBE layers to create lattice damage does not significantly affect the Be diffusion in a subsequent anneal.

Negative differential resistance has been observed at 300 K in a bilevel superlattice structure. Additional experimental data from conventional superlattice devices verify that this negative resistance is due to transitions in the bilevel superlattice. These devices demonstrate that the Hess real space transfer effect can be extended to the quantum well regime.

The optical modulation technique of photoreflectance (PR) has been applied to characterize the interband transitions in GaAs/AlGaAs multiple quantum wells (MQW) and modulation‐doped heterojunctions at room temperature. The spectra of the MQW show ‘‘derivativelike’’ reflectance features due to allowed interband transitions from heavy and light hole subbands to conduction subbands, and the E0(Γ8,v→Γ6,c) transitions of the AlGaAs layers. Our data are consistent with a square well calculation using a conduction‐band offset of 60% of the band‐gap discontinuity. For modulation‐doped heterojunctions, a correlation is observed between a PR feature approximately 18 meV above the GaAs fundamental gap and the presence of a two‐dimensional electron gas.

Iron‐doped GaAs layers have been grown by molecular beam epitaxy (MBE) over a substrate temperature range of 460–540 °C with incident 56Fe levels of 2×108–2×1011 atoms cm−2 sec−1. Photoluminescence studies indicate that iron can be incorporated on Ga sites in MBE GaAs. A pronounced accumulation of Fe at the outer epi‐layer surface is observed in secondary‐ion mass spectroscopy profiles of heavily doped samples. This accumulation leads to appreciable donor compensation in n‐type GaAs subsequently grown.

A new rectifying diode is proposed whose asymmetric current versus voltage characteristic originates from the ground state energies in an asymmetric sequence of quantum wells. Data are presented on devices fabricated from samples of this proposed structure grown by molecular beam epitaxy. These diodes exhibit current versus voltage temperature dependence and reverse bias capacitance which are different from other types of electron barrier devices.

Pure Al and Al0.5Ti0.5 targets were bombarded by Ar ions in the energy range 100 keV–3 MeV. For Ar energies between 260 keV and 1.25 MeV, it was found that the Al‐Ti target is a more intense emitter of Al K x rays than is the pure Al target. These findings are consistent with the predictions of a two‐step process in which Ar L‐shell vacancies produced in an Ar‐Ti collision are transferred to the K shell of an Al atom in a second collision.

A wide range of targets was bombarded with rare gas ions, mostly at 100 keV. Strong continua were observed in the 8-12eV (100-160 nm) range. They are due to the decay of bound-excited rare gas molecules (excimers). The dose dependence of the continuum intensity was measured. Also, experiments were performed in which targets previously implanted with one rare gas were impacted with another. Both the dose dependence and the mixed-projectile work indicate that the continuum arises from interactions involving implanted species. It may be possible to use excimer continuum intensity measurements to determine the depth distribution of implanted rare gas atoms.

Depth profiles for 60‐keV Al+ implanted in Si have been measured by SIMS analysis as a function of implant fluence and anneal temperature. A pronounced structure has been observed in the annealed profiles for fluences ⩾1015 cm−2. Comparison of the Al profiles with those of implanted B and Ga established that the structure is species dependent. The results of measurements designed to isolate damage effects indicate that the observed structure is induced by the reordering of the amorphous layer.

6H silicon carbide crystals have been subjected to 11B+ ion implantation and subsequent annealing and found to show the yellow boron photoluminescence.

The nature of the free electronic states in GaAs-GaAlAs quantum well (QW) structures has been the subject of extensive investigation over the past few years and is by now relatively well understood. For a number of reasons, impurity states confined in QW structures are not as well understood, and not until very recently have experimental investigations been undertaken1. Variational calculations2–4 for Hydrogenic impurities are in general agreement in their predictions of substantial shifts in the energy levels of the impurities relative to the bulk values as the width of the QW approaches the effective Bohr radius of the impurities. The magnitude of the shifts depends on the width and depth of the QW, as well as the position of the impurity within the well.

Uniformly prepared samples have been used for comparison of profiles using three techniques. Proton resonance is nondestructive and provides the best depth resolution at or near the surface. PRP was used as a quantitative standard for total number of particles and for absolute depth. However, the ability of PRP to resolve fine structure beyond the first few hundred angstroms is inferior to SIMS and AES. Proton Resoance Profiling is not expected to be widely used as a profiling technique because of the capital equipment costs and the limited number of impurity-host combination. However, this technique can be utilized to evaluate and calibrate other diagnostic techniques in a quantitative manner. Auger Electron Spectroscopy is a nondestructive surface analysis technique and is most sensitive to surface impurities. In order to profile with AES, the surface must be sputtered, thus destroying the sample. The limits of sensitivity are on the order of 0.1 atomic 7. Thus, the SIMS and PRP techniques are more sensitive for depth profiling of dopants and trace impurities. AES capital equipment costs, however, are signifi'cantly lower than the other two techniques and many surface oriented reliability problems can be effectively examined by AES. Secondary Ion Mass Spectrometry is the most sensitive of the techniques compared in this work and is capable of semiquantitative analysis of a wide range of dopants and impurities relevant to reliability studies. However, as with AES profiling the material is sputtered away thus destroying the sample.

Atomic, optically active, and electrically active profiles measured for 250 keV ion-implanted Be in GaAs as a function of fluence have been correlated. Be atomic depth profiles were obtained by secondary-ion mass-spectroscopy (SIMS) techniques. Photoluminescence and Hall effect measurements made in conjunction with successive layer removal were used to obtain the optically and electrically active profiles. Atomic SIMS profiles obtained from samples implanted to a fluence of 6X10113cm-2 showed no major distribution changes after a 900°C, 30 min anneal treatment. Electrically active profiles obtained from duplicate samples had distributions which were similar to the SIMS results. Hall effect and resistivity measurements after annealing indicated nearly complete electrical activity of the implanted Be, with mobility values typical of p-type bulk material.

Amorphous III-V materials present an interesting array of problems concerning the determination of their structure. They apparently exhibit short range tetrahedral order as do their elemental counterparts a-Si and a-Ge, but beyond nearest neighbor distances, fluctuations in bond lengths and bond angles lead to a more or less random arrangement of atomic sites in a manner qualitatively similar to that observed in a-Si and a-Ge.1 Dangling-bond defects (analogous to vacancies in crystals) in amorphous tetrahedral semiconductors have been studied a great deal although the vast majorities of both experimental and theoretical investigations have focused on a-Si and a-Si:H.2 The relationship between randomness imposed on a tetrahedral network and the presence of strains which are supposedly relieved by the formation of dangling bonds constitutes a controversial issue which still merits much study. However, in addition to those mentioned above, an even greater variety of intrinsic or native defects are expected to be present in a-III-V compounds than in a-Si of a-Ge due to local departures from stoichiometry and the possibility of bonding between like atoms (wrong bonds).