Silica capping for Al0.3Ga0.7As/GaAs and In0.2Ga0.8As/GaAs quantum well intermixing

Li, G.
Chua, S.J.
Xu, S.J.
Wang, X.C.
Saher Helmy, A.
Ke, Mao-Long
Marsh, J.H.

Publication date

December 1998

DOI

10.1063/1.122777

Publisher

AIP Publishing

Abstract

Spin-on silica capping has been demonstrated to be an effective dielectric encapsulant layer for quantum well (QW) intermixing at temperatures significantly lower than for conventionally deposited silica. A blueshift of up to 125 meV was observed in the photoluminescence (PL) peak energy of both GaAs and InGaAs QWs after annealing for less than 60 s at 850 °C, without noticeable degradation in the PL emission intensity. A threshold temperature was identified below which no significant QW disordering took place. The activation energy for Al diffusion in Al0.3Ga0.7As/GaAs QWs was about 2.55 eV. Broadly similar effects were seen for In0.2Ga0.8As/GaAs QWs but, in addition, strain effects appear to enhance disordering during the early stages of ...