First X-Ray Evidence of Heterogeneous Impurity Correlations in Very Highly Doped n-GaAs

Measurements of X-ray scattering from very highly doped GaAs:Te single crystals as a function of doping level and thermal treatment (annealing temperature) are reported. Reversible diffuse X-ray scattering occurs after sample annealing below a certain temperature. Presented results indicate an inhomogeneous arising of impurity-impurity correlations in GaAs:Te solid solution. Observed features of diffuse X-ray scattering in reciprocal space can be well understood within Krivoglaz theory of scattering due to spatial fluctuations of solute atoms pair correlation function and related lattice deformations. Good coincidence of diffuse X-ray scattering with the free electron concentration changes caused by an annealing is reported. Free electron concentration drop accompanying impurity correlation strongly suggests a certain form of impurity bonding

Te Shallow Donor Solubility Mechanism in GaAs

Results of thermal annealing of extremely highly doped GaAs:Te on room temperature Hall electron concentration and diffuse X-ray scattering are briefly reported. Reversible decrease/increase in electron concentration vs. temperature of annealing perfectly coincides with a strong increase/decrease in diffuse X-ray scattering intensity. An analysis of X-ray results indicates an arising of correlations in impurity positions in crystal lattice points in GaAs:Te solid solution for very high doping level. We give a sketch of a new formal model of tight bond creation between impurity atoms, which can consistently describe our results. The model is free from difficulties in describing annealing results encountered by a widely spread model of charge compensation by native acceptors

Infrared Optical and X-Ray Determination of Parameters for MOVPE Grown InAs1−x\text{}_{1-x}Sbx\text{}_{x} Epilayers

The experimental room-temperature transmission of metalorganic vapour phase epitaxy grown InAsSb epilayers is compared with calculations based on a Kane model of the band structure. The band structure parameters are found. The composition of the samples was determined by X-ray diffraction

Potential and Carrier Distribution in AlGaN Superlattice

Photocurrent spectroscopy and Kelvin force microscopy have been used in order to determine charge, field, and potential distributions in spontaneously grown superlattice. The spectra show that light can generate currents and potentials in both directions depending on photon energy. A numerical model made for superlattice of periodλ$\text{}_{SL}$ = 33 nm shows that electric field in superlattice oscillates coherently with Al content. The oscillations of electric field explain the different directions of photocurrent. The electric field can also separate electrons and holes, making carrier lifetimes longer and lowering excitation intensity threshold for occupation inversion