Photoluminescence of excitons in InxGa1-xN/InyGa1-yN multiple quantum wells
2002 (English)In: Physica status solidi. A, Applied research, ISSN 0031-8965, Vol. 190, no 1, 161-166 p.Article in journal (Refereed) Published
We report on a detailed study of excitons in InxGa1-xN/InyGa1-yN multiple quantum wells (MQWs) with an In composition x in the QWs of about 0.1, and a small In composition y in the barrier of 0.01-0.02. The MOVPE growth procedure was optimized to allow growth without In segregation. The InyGa1-yN barriers had a Si doping of about 5 x 10(18) cm(-3) . The low temperature photoluminescence spectra show two sets of exciton-like spectra with quite different properties. The lower energy emission has a small thermal activation energy (about 5 meV), and thus disappears at elevated temperatures, it is not observed at room temperature. The higher energy exciton state has a decay time of about 5 ns, while the lower energy process is much slower. We have also done preliminary studies on samples where the MQW region is situated in a p-n junction field, with semi-transparent contacts, to study the effects of varying the bias across the MQW structure. The combination of optical data can e interpreted in terms of a substantial potential gradient across the MQW region for both samples. The conclusion is that probably only one QW is emitting at low T (and no bias), and the second lower energy PL peak originates from a shallow notch in the conduction band at the interface between the thick GaN buffer layer and the first Ga(In)N barrier.
Place, publisher, year, edition, pages
2002. Vol. 190, no 1, 161-166 p.
Engineering and Technology
IdentifiersURN: urn:nbn:se:liu:diva-48720OAI: oai:DiVA.org:liu-48720DiVA: diva2:269616