Journals / Turkish Journal of Physics / 2004 / Cilt: 28 - Sayı: 6
Electrical Properties of Hydrogen Transport VPE Grown n-CdTe Epilayers on ZnTe/GaAs
- Journal
- Turkish Journal of Physics
- Pages
- 379–389
- DOI
- —
Abstract
Electrical characterisation of n-CdTe epilayers grown by hydrogen transport vapour phase epitaxy (H2T-VPE) on insulating ZnTe/(100)GaAs substrates through the temperature dependent Hall measurements is reported. Double-crystal X-ray diffraction assessments indicate the material high crystalline quality. Samples grown at temperatures, TG < 650 °C were p-type, but appeared to be n-type for the temperatures above TG > 650 °C. Hall measurements performed on n-type samples of different thicknesses grown at TG = 764 °C showed room temperature carrier densities in the range of 1011-1014 cm-3. The electron density and Hall mobility characteristics may be in principle well explained with a two-level affective model. The model of scattering by lattice and ionised impurity were found to be limiting dominantly the room temperature electron mobility. For a \sim 22 m m thick CdTe epilayers two donor levels were mainly estimated: The first, most abundant compensates partly 1018 cm-3 density of acceptors while the second with activation energy, Ed = 186 meV determines n-type electrical properties. A compensation ratio, 0.9997 holds for this epilayer. These could be possible formed through the diffusion of Ga atoms from GaAs into CdTe.
Özet
Electrical characterisation of n-CdTe epilayers grown by hydrogen transport vapour phase epitaxy (H2T-VPE) on insulating ZnTe/(100)GaAs substrates through the temperature dependent Hall measurements is reported. Double-crystal X-ray diffraction assessments indicate the material high crystalline quality. Samples grown at temperatures, TG < 650 °C were p-type, but appeared to be n-type for the temperatures above TG > 650 °C. Hall measurements performed on n-type samples of different thicknesses grown at TG = 764 °C showed room temperature carrier densities in the range of 1011-1014 cm-3. The electron density and Hall mobility characteristics may be in principle well explained with a two-level affective model. The model of scattering by lattice and ionised impurity were found to be limiting dominantly the room temperature electron mobility. For a \sim 22 m m thick CdTe epilayers two donor levels were mainly estimated: The first, most abundant compensates partly 1018 cm-3 density of acceptors while the second with activation energy, Ed = 186 meV determines n-type electrical properties. A compensation ratio, 0.9997 holds for this epilayer. These could be possible formed through the diffusion of Ga atoms from GaAs into CdTe.