AVS 49th International Symposium
    Electronic Materials and Devices Tuesday Sessions
       Session EL+SC-TuA

Paper EL+SC-TuA6
Deep Level Defect Characterization of InGaAsN Layers Grown by Molecular-Beam Epitaxy

Tuesday, November 5, 2002, 3:40 pm, Room C-107

Session: Semiconductor Characterization
Presenter: S.W. Johnston, National Renewable Energy Laboratory
Authors: S.W. Johnston, National Renewable Energy Laboratory
R.K. Ahrenkiel, National Renewable Energy Laboratory
A.J. Ptak, National Renewable Energy Laboratory
Correspondent: Click to Email
The quaternary alloy In@sub x@Ga@sub 1-x@As@sub 1-y@N@sub y@ can be grown lattice-matched to GaAs and can potentially be used as the 1-eV bandgap material in a four-junction, high-efficiency solar cell. We have characterized a series of In@sub x@Ga@sub 1-x@As@sub 1-y@N@sub y@ samples with varying N content by measuring deep level transient spectroscopy (DLTS). The samples were grown by rf plasma-assisted molecular-beam epitaxy and contain N concentrations 0@<=@y@<=@0.02. Our data show that each as-grown sample contains a hole trap whose peak occurs near 350 K for the 0.2-ms rate window. Analysis of these peaks indicates activation energies of 0.62, 0.62, and 0.75 eV for samples with y = 0.003, 0.013, and 0.02, respectively. Electron traps were also detected, even though the DLTS measurements were performed with Schottky contacts deposited on p-type material. This is attributed to a large Schottky barrier. For the sample with y = 0.003, an electron trap with an activation energy of 0.50 eV was detected. As N-content increased, the detected electron-trap activation energies decreased to 0.22 and 0.27 eV for the y = 0.013 sample, and to 0.13 eV for the y = 0.02 sample. We also show DLTS data correlating to varying growth conditions and the effects of annealing processes.