Acceptor energy level for Zn in Ga1−xAlxAs

Electrical properties and the acceptor energy level in Zn-doped p-Ga1−xAlxAs (0<x<0.85) prepared by liquid-phase epitaxy have been investigated. During the LPE growth of Zn-doped p-Ga1−xAlxAs layer, Zn diffuses from Zn-doped Ga-Al-As melt into the undoped n-GaAs substrate to form the p-GaAs region. The modified van der Pauw method proposed by Petritz was used to measure the electrical properties of p- (GaAl)As and p-GaAs. The resistivity and the hole concentration of Zn-doped p-Ga1−xAlxAs were found to be strongly affected by the acceptor energy level for Zn. The acceptor energy level in Zn-doped p-Ga1−xAlxAs was found to increase from 15 meV for x=0 to 90 meV for x=0.85. The increase of the acceptor energy level with increasing x has been theoretically explained by the modified hydrogenic model proposed by Baldereschi and Lipari.