Nanoscopically resolved dynamic charge-carrier distribution in operating interband cascade lasers

Abstract

ORIGINAL PAPER Abstract Dynamic charge carriers play a vital role in active photonic quantum/nanodevices, such as electrically pumped semiconductor lasers. Here we present a systematic exper- imental study of gain-providing charge-carrier distribution in a lasing interband cascade laser. The unique charge-carrier distribution profile in the quantum-well active region is quan- titatively measured at nanometer scales by using a noninva- sive scanning voltage microscopy technique. Experimental re- sults clearly confirm the accumulation and spatial segrega- tion of holes and electrons in the beating heart of the de- vice. The measurement also shows that the charge-carrier density is essentially clamped in the presence of stimulated emission at low temperatures. The threshold charge-carrier density exhibits a linear but fairly weak temperature depen- dence, in contrast to the exponential temperature depen- dence of the threshold current. The experimental approach will lead to a deeper understanding of fundamental pro- cesses that govern the operation and performance of nanoelec- tronic devices, quantum devices and optoelectronic devices.