Bright Emission at Reverse Bias After Trailing Edge of Driving Pulse in Wide InGaN Quantum Wells

Abstract

In group‐III‐nitride quantum wells (QWs), a strong piezoelectric field is formed. A built‐in potential from the p–n junction is working in the opposite direction depending on an externally applied voltage. Furthermore, the electric field in the QW can be partially screened by a high charge carrier density. Herein, the influence of these effects on recombination and spectrum for over 10 nm wide InGaN QWs is investigated. The very low overlap of electrons and holes would suggest inefficient devices. However, it is shown that thick QWs can be more effective and reach high optical gain. This can be explained by the screening of the electric field, resulting in a high overlap of excited electron and hole states that enable lasing. Herein, a pulsed electrical excitation scheme is used, where carrier injection at forward bias and predominant recombination at zero or reverse bias are separated in time. The interplay between the piezoelectric field and the built‐in potential on carrier recombination in dependence on an external bias voltage is observed. In particular, a strong increase of the radiative recombination rate after the trailing edge of the driving pulse is observed.