Low temperature (LT) and stoichiometric low temperature (SLT) MBE GaAs and related compounds: improved structural, electrical and optical properties

Abstract

GaAs and related materials grown at 200-300°C under normal, group V-rich growth conditions are highly non-stoichiometric with excess group V concentrations of up to 10 21 cm -3 . The material properties are, therefore, defect controlled. Here we further our previous studies of low-temperature grown GaAs to show that doping with Si or Be at concentrations at or greater than 10 19 cm -3 reduces the excess As related defect concentration by more than an order of magnitude, not only on GaAs(1 0 0) but also on GaAs(3 1 1)A and GaAs(3 1 1)B surfaces, compared to undoped material grown under identical conditions. Furthermore, we show that by careful control of the As: Ga flux ratio at low temperature, stoichiometric low-temperature (SLT) conditions may be achieved which can be used to grow GaAs, AlGaAs and other III-V compounds of electrical and optical performance comparable to material grown at high temperatures. SLT quantum well (QW) structures of AlGaAs/GaAs and SLT QW and two-dimensional electron gas (2DEG) structures of InAlAs/InGaAs, lattice matched to InP, are used to demonstrate the excellent quality material achievable and how it may be applied to optical and electrical devices. The work illustrates the wide range of material benefits which can be attained in the low-temperature growth regime.