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The purpose of the study is to investigate the effect of a new type of compliant substrate based on an AlGaAs superstructure layer (SL) and a protoporous Si (proto-Si) layer formed on a crystal Si (c-Si) layer on the practical implementation and specific features of the epitaxial growth of GaAs layers by metal–organic chemical vapor deposition. It is for the first time shown that the low-temperature growth of high-crystal-quality epitaxial GaAs films can be implemented due to the use of compliant SL/proto-Si substrates. The introduction of a SL into the composition of a compliant substrate in addition to proto-Si makes it possible to neutralize a number of negative effects of low-temperature growth, to reduce the level of stresses in the epitaxial layer, to protect it from self-doping with Si atoms, to reduce the number of technological operations of the growth of transition buffer layers, and to improve the structural and morphological characteristics of the epitaxial layer. [ABSTRACT FROM AUTHOR]

The purpose of the study is to investigate the effect of a new type of compliant substrates based on an AlGaAs superstructure layer (SL) and a protoporous Si (proto-Si) layer formed on a crystalline Si (c-Si) layer on the optical properties of an epitaxial GaAs layer grown by metal–organic chemical vapor deposition. It is for the first time shown that the low-temperature growth of high-quality epitaxial GaAs films can be conducted using SL/proto-Si compliant substrates. The introduction of a SL layer in addition to proto-Si into the composition of the compliant substrate makes it possible to mitigate a number of negative effects of low-temperature growth, to reduce the level of strains in the epitaxial layer, to protect it from self-doping with Si atoms, to reduce the number of technological operations of the growth of transition buffer layers, to improve the structural and morphological characteristics of the epitaxial layer, and to attain good optical characteristics of the layer. The GaAs/Si heterostructures are studied by Raman spectroscopy, photoluminescence measurements, and optical transmission–reflection spectroscopy. The data will serve as an important material for understanding the fundamentals of the physics and technology of integrated III–V/Si heterostructures and for facilitating their use in optoelectronic devices. [ABSTRACT FROM AUTHOR]

Graphene films were synthesized with the method of chemical vapor deposition using gaseous methane as the source of carbon and copper foil as the substrate for the deposition. The following conditions were found optimal to grow large-area high quality graphene films: preliminary annealing of the foil in the argon/hydrogen mixture at 970-990 °С for 30-40 min; simultaneous supply of the argon/hydrogen mixture (100 cm3/min) and methane (10 cm3/min) for 5-10 minutes, and subsequent cooling in an inert atmosphere. As a result, 1-10 layered graphene films were obtained to fully coat the copper foil over the area up to 50 cm2. Several methods have been developed to transfer graphene to dielectric substrates such as silicon oxide and flexible polymer films. The obtained graphene films were used to create a flexible transparent conductive touch panel and a highly sensitive resistive humidity sensor exhibiting fast response-recovery time. [ABSTRACT FROM AUTHOR]

The influence of the degree of misorientation and treatment of a GaAs substrate on the structural and optical characteristics of homoepitaxial GaAs/GaAs(100) structures grown by metal-organic chemicalvapor deposition is studied. From the data obtained by a series of structural and spectroscopic techniques, it is shown that the degree of deviation of the substrate from the exact orientation towards the [110] direction by an angle of up to 4° brings about stepwise growth of the GaAs film in the initial stage and a further increase in the degree of misorienration towards the [110] direction to 10° results in an increase in the number of structural defects in the epitaxial film. At the same time, the samples of homoepitaxial structures grown by metal-organic chemical-vapor deposition on GaAs(100) substrates misoriented by 4° towards the [110] direction possess the highest photoluminescence efficiency; it is ~15% higher than the corresponding quantity for structures grown on precisely oriented GaAs(100) substrates. Preliminary polishing of the GaAs substrate (removal of an oxide layer) also yields the intensification of photoluminescence emission compared to emission in the case of an unpolished substrate of the same type. For samples grown on substrates misoriented by 4°, such an increase in the photoluminescence efficiency is ~30%. [ABSTRACT FROM AUTHOR]

The properties of epitaxial GaInP alloys with an ordered arrangement of atoms in the crystal lattice are studied by a number of structural and microscopic methods. The alloys are grown by metal-organic chemical vapor deposition onto single-crystal GaAs(100) substrates. It is shown that, under conditions for the coherent growth of an ordered GaInP alloy on a GaAs(100) substrate, atomic ordering results in radical modifications of the structural properties of the semiconductor compared to the properties of disordered alloys. Among these modifications are a change in the crystal-lattice parameter and, as a consequence, lowering of the crystal symmetry and the formation of two different types of surface nanorelief. With consideration for elastic strains, the parameters of GaInP alloys with ordering as functions of the order parameter are calculated for the first time. It is shown that all experimental data are in good agreement with the developed theoretical concepts. [ABSTRACT FROM AUTHOR]

Structural and spectroscopic methods are used to study the epitaxial layers of n-type AlGaAs solid solutions produced by the metal-organic chemical vapor deposition method. It is shown that, when AlGaAs solid solutions are doped with carbon to a level of (1.2-6.7) × 10 cm, the electron mobility is anomalously high for the given impurity concentration and twice exceeds the calculated value. It is assumed that the ordered arrangement of carbon in the metal sublattice of the solid solution leads to a change in the average distance between impurity ions, i.e., to an increase in the mean free path of the carriers and, consequently, in the carrier mobility. The observed effect has immediate practical importance in the search for various technological ways of increasing the operating speed of functional elements of modern optoelectronic devices. The effect of the anomalously high carrier mobility in the epitaxial layer of a heteropair opens up new opportunities for the development of new structures on the basis of AlGaAs compounds. [ABSTRACT FROM AUTHOR]

Laser heterostructures with an active region consisting of a highly strained GaInAs quantum well located between GaAsP compensating layers were grown by metal-organic chemical vapor deposition on GaAs substrates. Stripe mesa-structure laser diodes of 100 μm aperture emitting at 1190 nm were fabricated. The highest emission power of these diodes in the CW mode amounted to 4.5 W per output mirror. Due to the presence of compensating GaAsP barriers, the GaInAs quantum well remains unrelaxed, which eliminates the spread in the maximum emission power of laser diodes produced from the same heterostructure. [ABSTRACT FROM AUTHOR]

A metal-organic chemical vapor deposition (MOCVD) technique is developed for a diode laser heterostructure in a system of InGaAs/GaAs/AlGaAs solid solutions; the optimal sizes and the doping profile of the structure are determined to minimize the internal optical losses. Mesa-strip diode lasers with a threshold density of current J[sub th] = 150-200 A/cm², internal optical loss factor (α[sub i] = 1.6-1.9 cm[sup -1], and an internal quantum yield η[sub i] = 85-95 % were fabricated. In the continuous lasing mode of a diode laser with a 100-µm-wide aperture and a wavelength of 0.98 µm, the optical power output was as high as 6.5 W and was limited by the catastrophic optical degradation of mirrors. The radiation divergence in the plane normal to the p-n junction amounts to θ[sub ⊥] = 25°-30°. The use of wide-gap waveguide layers, which deepens the potential electron well in the active region, is shown to reduce the temperature sensitivity of the InGaAs/GaAs/AlGaAs laser heterostructures in the temperature range from 0 to 70°C. [ABSTRACT FROM AUTHOR]

Heterostructures comprising highly strained GaAs quantum wells in Al0.48In0.52As and Ga0.47In0.53As layers have been grown by the metalorganic chemical vapor deposition method on InP(100) substrates. The photoluminescence spectra of these structures have been studied, and it is established that GaAs quantum wells form type-I heterojunctions with Al0.48In0.52As layers and type-II heterojunctions with Ga0.47In0.53As layers. [ABSTRACT FROM AUTHOR]

We have studied the photoluminescence of heterostructures based on solid solution systems of the GaInP/GaAsP/GaInAsP type grown by metalorganic chemical vapor deposition method. It is established that GaAs0.77P0.23 and Ga0.74In0.26As0.53P0.47 solid solutions form a type-II heterojunction. The conduction band offset at the GaAs0.77P0.23 /Ga0.74In0.26As0.53P0.47 heteroboundary amounts to 90 meV, which makes the quaternary solid solution a preferred material for the active region of a laser heterostructure operating at λ = 780 nm. © 2004 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]