LOW-TEMPERATURE (LT) AND STOICHIOMETRIC LOW-TEMPERATURE (SLT) MBE GAAS AND RELATED-COMPOUNDS - IMPROVED STRUCTURAL, ELECTRICAL AND OPTICAL-PROPERTIES

GaAs and related materials grown at 200-300 degrees C under normal, gr oup V-rich growth conditions are highly nonstoichiometric with excess group V concentrations of up to 10(21) cm(-3). The material properties are, therefore, defect controlled. Here we further our previous studi es 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 o nly 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. Furthe rmore, we show that by careful control of the As:Ga flux ratio at low temperature, stoichiometric low-temperature (SLT) conditions may be ac hieved which can be used to grow GaAs, AlGaAs and other III-V compound s of electrical and optical performance comparable to material grown a t high temperatures. SLT quantum well (QW) structures of AlGaAs/GaAs a nd 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 be nefits which can be attained in the low-temperature growth regime.