Shallow donors and <i>D</i>-<i>X</i> centers neutralization by atomic hydrogen in GaAlAs doped with silicon

Abstract

Hydrogen plasma exposure of silicon-doped Ga1−xAlxAs epilayers with x&amp;lt;0.37 causes a strong reduction of the free-electron concentration in the layers. For x&amp;lt;0.29, this effect is accompanied by a simultaneous increase of the electron mobility. This is interpreted, as in GaAs, in terms of a neutralization of the active silicon donors by atomic hydrogen. The neutralization efficiency of the shallow donors increases as x increases. For x≂0.25, the D-X centers are very efficiently neutralized by hydrogen and, as a consequence, the conductivity mechanisms after exposure are only governed by the remaining shallow donors. For 0.29&amp;lt;x&amp;lt;0.37, most of the D-X centers are neutralized, but the electron mobility after hydrogenation is reduced.