Photoluminescence study of Sr+ ion-implanted GaAs

Abstract

Low-temperature photoluminescence experiments were carried out for Sr+ ion-implanted GaAs substrates as a function of Sr concentration and excitation intensity. It was found that the Sr impurity produces four emissions denoted by (Sr°, X), ‘‘G1’’, ‘‘G2’’, and ‘‘H’’ in the near band emission region in GaAs grown by molecular beam epitaxy. ‘‘G1’’ emission presents a red shift with increasing Sr concentration, while ‘‘G2’’ does not shift. In a Sr+ ion-implanted impure GaAs substrate grown by the liquid-encapsulated Czochralski method, all four of the above emissions were missing. Instead there appeared two other emissions, SM1 and SM2, which are considered to be related to two deep acceptor levels of Sr in GaAs. All results indicate that the Sr impurity produces both shallow and deep energy levels in GaAs and a small amount of the residual impurity will quench the emissions related to shallow energy levels.