Te doping of GaAs and Al xGa 1− xAs using diethyltellurium in low pressure OMVPE

Abstract

The incorporation of Te in Al x Ga 1− x As grown by low pressure OMVPE using diethyltellurium (DETe) has been studied as a function of Al composition ( X = 0−0.4), vapor phase V/III ratio, doping level (i.e., DETe vapor mole fraction), and growth temperature T s . Variable temperature Hall effect measurements ( T = 20−400 K) have shown that, for a given alloy composition X Al' the “donor activation energy”, (i.e., the slope of log ( 1 eR H ) versus 1 T ) is smaller in Te doped Al xGa 1−xAs than in Si doped AlGaAs (e.g., 18 versus 60 meV for X Al = 0.3). A maximum 300 K carrier concentration of n = 1×10 19 cm −3 was obtained in Te-doped GaAs. The 300 K carrier concentration n 300 in Te doped GaAs decreased with increasing vapor phase V/III ratio (e.g., n = 5.0×10 17 cm −3 at a V/III ratio of 20 compared with n = 1.5×10 17 cm −3 at a V/III ratio of 120). The value of itnin300 also decreased with increasing growth temperature (e.g., n 300 = 2.3×10 18 cm −3 at T s = 600° C and n 300 = 8×10 16 cm −3 at T s = 750° C). Trends in the Hall mobility, photoluminescence efficiency at 300 K, and surface morphology are presented, and the Te doping “memory effect” will be discussed.