Search

We have measured the precise lattice parameter of undoped and impurity-doped ZnSe single crystals by the Fewster method. The lattice parameter of undoped ZnSe single crystals was 0.566919±0.000002 nm and it remained unchanged after the Zn-treatment at 1000°C. On the other hand, dilation of lattice parameter observed in I-doped ZnSe depended on Zn-treatment temperature. Increase of lattice parameter also occurred in Al-doped ZnSe. These results suggest that I and Al impurities in ZnSe crystal play an important role with point defects formation during and after the Zn heat treatment.

Lattice parameters of annealed ZnSe crystals have been measured by the Bond method. The annealing was carried out at 1000°C under a definite Zn partial pressure maintained by heating a Zn reservoir after growth from the melt under Zn partial pressure. The lattice parameter, a , depends on the Zn reservoir temperature during annealing, T Zn (A); a =0.566898±0.000005 nm at T Zn (A) of 450–600°C, a =0.566910±0.000005 nm at T Zn (A) of 750°C and a =0.566913±0.000003 nm at T Zn (A) of 900°C. The dependence of lattice parameter on Zn partial pressure is discussed.

Dependence of the lattice parameter of melt-grown ZnSe on Zn partial pressure have been measured by the Bond method. The lattice parameters changed between 0.566902 and 0.566908 nm depending on the partial pressure of Zn during growth. The minimum lattice parameter was observed at the Zn reservoir temperature of 1000°C, where the melt composition was near stoichiometry.

The refractive indices and lattice constants of large KTP single crystals grown from a flux of K 6 P 4 O 13 have been investigated. Changes in their refractive index and lattice constant along the growth direction result from compositional deviation of the solution. Strong correlation is implied in the similar behavior of both the lattice constant and the refractive index. The lattice constant dependence on the compositional deviation seems to be due to variations in the solid solution range among the KTP components.

LiNbO3 films of higher crystalline quality than underlying LiNbO3 substrates have been successfully grown from a solid-liquid coexisting melt using a new liquid phase epitaxial technique. The dependence of crystallinity and lattice mismatch on film thickness and growth temperature has been investigated in detail through X-ray rocking curve analysis.

This article reports the notable effect of N doping in ZnSe on the band-gap energy. The free exciton energy in the epilayers with different N A − N D was measured by means of reflectance and photoreflectance spectroscopies. The temperature dependence of reflectance, photoreflectance and photoluminescence spectra of ZnSe:N epilayers was investigated in detail. It is found that the free exciton energy shifts to low energy side with increasing N concentration, indicating the shrinkage of the band-gap energy due to N doping. The peak positions of near-band-edge emissions shift to low energy side due to the shrinkage of energy gap. The lattice constant and the strain in N-doped ZnSe were measured by means of X-ray diffraction (XRD). The origins for the shrinkage of energy gap are discussed on the basis of the optical and XRD results.

AlAs/Al/AlAs heterostructures are fabricated on (001)GaAs by molecular beam epitaxy (MBE) and migration enhanced epitaxy (MEE). The Al and successive AlAs layers are grown at room temperature by MBE and MEE, respectively, while the underlying AlAs layer is grown at 600°C by MBE. Single crystal Al layers are grown successfully. The epitaxy relationship of Al with the underlying AlAs layer is (011)[100]Al‖(001)[110]AlAs. Detailed RHEED analysis elucidates the lattice relaxation processes of Al on AlAs as well as the growth process. It is suggested that the initially deposited 2(1) ML thick Al layers occupy sublattice sites in the AlAs lattice with the same lattice spacing as AlAs on As- (Al-) stabilized AlAs and that the lattice relaxation and the formation of the fcc Al lattice is initiated during deposition of the 3rd (2nd) layer on As- (Al-) stabilized AlAs. The top AlAs layer is single crystalline and grows in an island growth mode. The observed epitaxy relationship of AlAs on Al is (001)[110]AlAs‖(011)[100]Al.

The effect of lattice deformation on optical properties and lattice parameters of ZnSe thin films, whose thickness ranges from 0.05 to 22 μm, grown by either atomic layer epitaxy or molecular beam epitaxy on (100)GaAs substrates, has been investigated. It is observed from the X-ray analysis that ZnSe layers thinner than 1μm suffer two-dimensional compressive stress due to the lattice misfit, while those thicker than ca. 1 μm suffer two-dimensional tensile stress due to the difference in the thermal expansion coefficients. It is found that the valence band structure of the epitaxial ZnSe film is modified considerably due to the residual stress. The energy shifts of excitonic emissions in the photoluminescence spectra and of exciton resonance dips in the reflectance spectra are consistent with the stress as investigated by X-ray analysis.