ABSTRACT
Band Gap 119 5.3 INTERBAND TRANSITIONS OF (Ga,In)(N,As)-
BASED HETEROSTRUCTURES 129 5.3.1 Ga(N,As)/GaAs QWs 130
5.3.1.1 Conduction-band structure and band alignment 130
5.3.1.2 Theoretical modeling 134 5.3.1.3 Comparison of experiment and theory 141
5.3.2 (Ga,In)(N,As)/Ga(N,As) QWs 145 5.3.2.1 Conduction-band structure and band
alignment 145 5.3.2.2 Type I-Type II transition 146
5.4 SUMMARY AND CONCLUSIONS
153 Acknowledgments 155 References 155
5.1 INTRODUCTION
This chapter presents an overview of the present knowledge of the electronic states of (Ga,In)(N,As)/Ga(N,As) quantum-well (QW) structures. The unusual band-formation process, when incorporating small amounts of N into (Ga,In)As and GaAs semiconductor hosts, results in a rather complex band structure of bulk (Ga,In)(N,As) and Ga(N,As) [1-10]. Appropriate theoretical concepts for describing the band structure of these materials are currently developed [11-26]. Furthermore, there exists a structural metastability of the quaternary alloy Gai_yInyNxAs,, that arises due to subtle microscopic effects when both In and N are present. As one result, the band-gap of Ga,_yInyN„Asi, is not simply a function of composition y and x, but also depends strongly on the material history, e.g., growth conditions as well as annealing conditions. Therefore, to understand this class of semiconductor materials, it is essential to correlate structural and electronic investigations.
