Lattice strain from DX centers and persistent photocarriers in Sn-doped and Si-doped Ga1−xAlxAs

Abstract

The lattice strain caused by electron emission from DX centers was determined by x-ray diffraction for Sn-doped and Si-doped ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Al}}_{\mathit{x}}$As, with ${\mathit{x}}_{\mathrm{Al}}$=0.22–0.24. Measurements were made after cooling samples to 14 K in the dark, which filled DX centers and thereby produced low conductivity. The measurements were repeated after emptying the DX centers by ir illumination, giving Δ${\mathit{N}}_{\mathit{e}}$=(1.0-1.6)×${10}^{18}$ ${\mathrm{cm}}^{\mathrm{-}3}$ conduction electrons which persisted after illumination. The ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Al}}_{\mathit{x}}$As:Sn lattice parameter increased on illumination, Δa/(aΔ${\mathit{N}}_{\mathit{e}}$)=+(7.9±2)×${10}^{\mathrm{-}24}$ ${\mathrm{cm}}^3$. The ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Al}}_{\mathit{x}}$As:Si lattice parameter also increased on illumination, Δa/(aΔ${\mathit{N}}_{\mathit{e}}$)=+(6.0±2)×${10}^{\mathrm{-}24}$ ${\mathrm{cm}}^3$.