The effects of hydrogenation in high-purity p-type GaAs grown by molecular beam epitaxy and metalorganic chemical vapor deposition have been investigated by low-temperature photoluminescence and Hall-effect measurements. Before hydrogenation, photoluminescence measurements showed the dominant acceptor in the original samples was C, while after hydrogenation, the concentration of electrically active C acceptors was significantly reduced and the samples were highly resistive. These electrical and spectroscopic results show that C acceptors in GaAs can be passivated by hydrogenation.

Zn and an unidentified acceptor species, labeled A1, are the only residual acceptors that have been observed in a wide variety of undoped high-purity InP samples grown by metalorganic chemical vapor deposition. Carbon is not incorporated at detectable concentrations as a residual acceptor in metalorganic chemical vapor deposited InP. However, the longitudinal and transverse optical phonon replicas of the free-exciton recombination occur at the same energy as the donor/conduction band-to-acceptor peaks for C acceptors in low-temperature photoluminescence spectra. Since these replicas are usually present in photoluminescence spectra measured under moderate or high optical excitation, care must be exercised so that these peaks are not misinterpreted as C-related transitions.

Influence of Fe segregation at grain boundaries on the magnetoresistance of Sr2Fe1+δMoO6 polycrystals J. Appl. Phys. 112, 073925 (2012) Angular-dependences of giant in-plane and interlayer magnetoresistances in Bi2Te3 bulk single crystals Appl. Phys. Lett. 101, 152107 (2012) Hall effect measurements on InAs nanowires Appl. Phys. Lett. 101, 152106 (2012) Magnetic field-dependent effective microwave properties of microwire-epoxy compositesThe decrease in the measured Hall free-electron concentration with decreasing temperature near 300 K is often observed for thin high-purity GaAs layers. This has previously been interpreted as electron freezeout on deep donor sites. However, it can be quantitatively described by the decrease in carrier concentration per unit area associated with increasing surface and interface depletion region thicknesses. It is shown that when these depletion regions are included in the analysis of the Hall-effect data, the measured free-electron freezeout behavior can be accurately described by a simple shallow donor. If necessary, a deep donor may be included in the modeling. The results agree with the observed temperature variation of the capacitance-voltage (C-V) profiling data.