title: Opposite carrier dynamics and optical absorption characteristics under external electric field in nonpolar vs. polar InGaN/GaN based quantum heterostructures.
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.
authors: Department of Electrical and Electronics Engineering, Department of Physics and UNAM–Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Bilkent, Ankara, Turkey.
authors: Emre
authors: E
authors: Sari
authors: Sedat
authors: S
authors: Nizamoglu
authors: Jung-Hun
authors: JH
authors: Choi
authors: Seung-Jae
authors: SJ
authors: Lee
authors: Kwang-Hyeon
authors: KH
authors: Baik
authors: In-Hwan
authors: IH
authors: Lee
authors: Jong-Hyeob
authors: JH
authors: Baek
authors: Sung-Min
authors: SM
authors: Hwang
authors: Hilmi Volkan
authors: HV
authors: Demir