Opposite carrier dynamics and optical absorption characteristics under external electric field in nonpolar vs polar InGaN/GaN based quantum heterostructures

Abstract

Abstract:We report on the electric field dependent carrier dynamics and optical absorption in nonpolar a-plane GaN-based quantum heterostructures grown on r-plane sapphire, which are surprisingly observed to be opposite to those polar ones of the same materials system and similar structure grown on c-plane. Confirmed by their time-resolved photoluminescence measurements and numerical analyses, we show that carrier lifetimes increase with increasing external electric field in nonpolar InGaN/GaN heterostructure epitaxy, whereas exactly the opposite occurs for the polar epitaxy. Moreover, we observe blue-shifting absorption spectra with increasing external electric field as a result of reversed quantum confined Stark effect in these polar structures, while we observe red-shifting absorption spectra with increasing external electric field because of standard quantum confined Stark effect in the nonpolar structures. We explain these opposite behaviors of external electric field dependence with the changing overlap of electron and hole wavefunctions in the context of Fermi"s golden rule. ©2011 Optical Society of America References and links1. S. Nakamura, M. Senoh, N. Iwasa, and S. Nagahama, "High power InGaN single-quantum-well-structure blue and violet light-emitting diodes," Appl. Phys. Lett. 67(13), 1868-1870 (1995). 2. S. Nakamura, M. Senoh, S. Nagahama, N. Iwasa, T. Yamada, T. Matsushita, Y. Sugimoto, and H. Kiyoku, "Room-temperature continuous-wave operation of InGaN multi-quantum-well structure laser diodes," Appl. Phys. Lett. 69(26), 4056-4058 (1996).

Lateral carrier confinement in InGaN quantum-well nanorods

“…Benefiting from the absence of piezoelectric polarization in the a-plane samples, the wave functions of electrons and holes in the a-plane samples are better overlapped than that in the c-plane samples [44,45]. As a consequence, the carrier recombination is much faster in the a-plane samples, so that the trapping effect of surface states is less distinct in the TRPL spectra [64,65].…”