Comprehensive analysis of Si-doped Al x Ga 1-x As (x=0 to 1): Theory and experiments

摘要: Temperature-dependent Hall-effect measurements were carried out both in dark and ambient light on Si-doped ${\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$ layers grown by molecular-beam epitaxy over the entire composition range. Above 150 K, measured Hall carrier densities (different from actual electron near direct-indirect transition) show an exponential dependence temperature. A shallow donor (\ensuremath{\le}15 meV) tied to $\ensuremath{\Gamma}$ band a deep level $L$ observed. The is dominant for $xg0.2$, its activation energy ${E}_{d}$ rises dramatically up band-gap crossover peaks at 160 meV $x\ensuremath{\sim}0.48$. As A1 fraction increases further, decreases, reaching 57 AlAs. error due multivalley conduction values of shown be negligible. variation with $x$ accounted our theoretical calculations using effective-mass model. decrease increasing doping also At high substrate-growth temperature, incorporation Si atoms was found decrease. persistent-photoconductivity (PPC) effect observed increase mobilities most pronounced range $0.20\ensuremath{\le}x\ensuremath{\le}0.40$. Traps related Si-doping density appear responsible photoconductivity effect. ratio PCC traps atomic maximum $x\ensuremath{\sim}0.32$ minimum region.