Journal of Crystal Growth, Vol.496, 36-42, 2018
Hall characterization of epitaxial GaSb and AlGaAsSb layers using p-n junctions on GaSb substrates
The Hall Van-der-Pauw method is widely used to assess the electrical properties of GaSb based semiconductor layers. Semi-insulating GaSb substrates are not available, and therefore, Hall structures are generally grown on semi-insulating GaAs. The lattice mismatch of 7.8% between GaAs and GaSb results in high defect densities, which may influence the measurement. We investigated an alternative approach for Hall effect measurements using a p-n junction for the electrical isolation of the test layer from layers below. This allows antimonide based test layers with low defect density grown lattice-matched on GaSb substrates to be analyzed. Negligible leakage currents across the p-n junctions are key to ensure significant measurement results, n- and p-GaSb layers show similar carrier concentration if grown on GaSb or semi-insulating GaAs, with the exception of highly n-doped layers > 5x10(17)cm(-3). However, majority carrier mobilities were systematically higher on GaSb substrate, explained by a lower density of structural defects. Furthermore, the sample design with p-n junction enabled Hall effect measurements of quaternary p-Al-0.2Ga0.8As0.02Sb0.98 layers, which was impossible for those same layers grown on GaAs due to strain induced phase-separation. The methodology is presented for antimonides, but it is applicable to a wide range of material systems including metamorphic structures.
Keywords:A1 Hall measurements;A1 Doping;A3 Metalorganicvapor phase epitaxy;B1 Antimonides;B1 Gallium compounds;A1 Majority carrier properties