β-Ga2O3 is a wide bandgap semiconductor that is attractive for various applications, including power electronics, transparent conductive electrodes, etc. Electrical and optical properties of Ga2O3 are affected by the presence of dopants/contaminants and/or intrinsic defects. Here, we investigate the electrical and optical properties of transition metals like Co and Cr since they are often unintentionally present during the growth or used as intentional dopants. This is done by using magnetic resonance spectroscopy and magneto-optical characterization techniques. We determine spin- Hamiltonian parameters of the Cr3+ ground-state and first excited-state as well as the spin-Hamiltonian parameters of Co2+.
A brief review is given of our recent experimental results from in-depth investigations of spin depolarization and underlying physical mechanisms within semiconductor spin detectors based on II-VIs (e.g. Zn(Cd)Se quantum wells) and III-Vs (e.g. InGaN quantum wells), which are relevant to applications for spin-LEDs based on ZnMnSe/Zn(Cd)Se
and GaMnN/InGaN structures. By employing cw and time-resolved magneto-optical and optical spin orientation spectroscopy in combination with tunable laser excitation, we show that spin depolarization within these spin detectors is very efficient and is an important factor limiting efficiency of spin detection. Detailed physical mechanisms leading to efficient spin depolarization will be discussed.
The principle, capabilities, advantages and limitations of the optically detected magnetic resonance (ODMR) technique will be briefly described. The ability of the ODMR technique to provide important information on physical properties of semiconductor thin films and layered structures will be highlighted. These include chemical identification, electronic and geometric structures of defects, carrier recombinations, etc. The important role in providing valuable feedback for improvement of growth process and in engineering material properties for device applications will be demonstrated. Representative cases from Si/SiGe- and InP- based structures grown by molecular beam epitaxy will be discussed as examples. The most recent progress, on-going efforts and prospects in achieving unprecedently high spectral, time and spatial resolution of the ODMR technique, meeting the demands and challenges raised by the increasing miniaturization of future electronic and optoelectronic devices, will also be outlined.
Conference Committee Involvement (1)
Ultrafast Phenomena in Semiconductors and Nanostructure Materials XI
22 January 2007 | San Jose, California, United States
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