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

Abstract

Dynamic charge carriers play a vital role in active photonic quantum/nanodevices, such as electrically pumped semiconductor lasers. Here we present a systematic experimental 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 quantitatively measured at nanometer scales by using a noninvasive scanning voltage microscopy technique. Experimental results clearly confirm the accumulation and spatial segregation of holes and electrons in the beating heart of the device. 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 dependence, in contrast to the exponential temperature dependence of the threshold current. The experimental approach will lead to a deeper understanding of fundamental processes that govern the operation and performance of nanoelectronic devices, quantum devices and optoelectronic devices.

Nanoscopic voltage distribution of operating cascade laser devices in cryogenic temperature

“…(,c) for voltage profiling of buried heterostructure (BH) laser devices that was for room temperature measurements only, and the setup was then developed and customized to the one used by Dhar et al . (,b, ), to satisfy the special requirements for cryogenic temperature SVM measurement of THz QCLs. A diamond‐coated conductive cantilever probe from Bruker, USA with spring constant = 42 N m –1 , model no.…”

“…From this mapping the local potential properties, such as electric field distribution due to dynamic carriers, in the semiconductor device is acquired without destroying the operating device (Ban et al ., ; Ban et al ., ,b; Dhar et al ., ,b). SVM has been successfully used to image the quantum structures on the nanometer scale device and also to resolve and measure inner workings such as voltage profiles, electric fields and their carrier distribution and in some instances also estimate the dynamic carrier concentration in operating III–V material‐based nanodevices (Ban et al ., ,b; Dhar et al ., ,b; Dhar et al ., ). Due to high spatial resolution of the AFM probe, SVM measurement resolved the structural layers accurately from the voltage profiling of the mapped image.…”

Nano-composite based Smart Electrochromic Device with escalated transmittance

“…Electrochemical analysis of the nanocomposite based EMD is investigated for ± 1.5V with 50mV/s scan rate in 1M Ferrocene of 98% purity. Cyclic voltammetry analysis is carried out which signi es that the redox response for both bleaching and colouration condition takes place within the nano-membranes of the electrochemical cell [22,23,24]. This initiates the quantum tunnelling process due to carrier transportation in the EMD.…”