N ELSEVIER Applied Surface Science 93 (1996) 131-134 surface science Determination of the subband carrier densities in a strained GaAs/Ino.15Gao.85As/Alo.z2Gao.7aAs single quantum well using photoluminescence T.W. Kim *, M. Jung, D.U. Lee Department of Physics, Kwangwoon University, 447-1 Wolgye-dong, Nowon-ku, Seoul 139-701, South Korea Received 2 August 1995; accepted for publication 12 September 1995 Abstract Photoluminescence (PL) measurements on a strained GaAs/Ino.15Gao.ssAs/Alo.22Gao.7sAs single quantum well grown by molecular beam epitaxy were performed to determine the subband carrier densities in the InoAsGao.85Assingle quantum well. The PL results obtained from the samples with two populated electron subbands were dominated by two spectral bands. The electronic subband energies and the Fermi energy in the Ino.15Gao.ssAs quantum well were calculated by a self-consistent method taking into account exchange-correlation effects together with strain and nonparabolicity effects. The subband carrier densities determined using the PL spectrum were in good agreement with those obtained from self-consistent calculation results and Shubnikov-de Haas measurements. These results clearly demonstrate the feasibility of using PL measurements, which involve no sample destruction, to determine subband carrier densities. PACS: 68.55. Bd; 73.20. Dx; 73.25. +i I. Introduction Recently, rapid advancements in epitaxial film growth technology have made possible the fabrica- tion of several new types of strained quantum wells [1-3]. More recently, experimental and theoretical studies of the two-dimensional electron gas (2DEG) in various strained InxGa]_xAS quantum structures have been performed [4,5]. Pseudomorphic GaAs/ InxGa j xAs/AlyGal_yAs modulation-doped Corresponding author. strained quantum wells are attractive due to their having a higher achievable 2DEG density and more confinement of the carriers in the quantum well channel due to the larger conduction band disconti- nuity resulting from the smaller energy gap and effective mass of InxGa l_xAs. In addition, effective device performance in the microwave frequency re- gion is achieved by incorporation of a pseudomor- phic In xGal - xAs strained quantum well [4-11 ]. Shubnikov-de Haas (SdH) and Hall effect mea- surements have been used commonly to determine the carrier density of the mobile electrons at low temperature; ohmic contacts are required for those 0169-4332/96/$15.00 © 1996 Elsevier Science B.V. All rights reserved SSDI 0169-4332(95)00325-8