High purity liquid phase epitaxial GaAs for radiation detectors
- Lawrence Berkeley National Lab., CA (United States)
The authors report on the growth of high purity n-GaAs using Liquid Phase Epitaxy (LPE) and the fabrication of room temperature p-i-n radiation detectors. The epilayers are grown from a Ga solvent in a graphite boat in a pure hydrogen atmosphere. Growth is started at a temperature of approximately 800 C. The best epilayers show a net-residual-donor concentration of 2 {times} 10{sup 13} cm{sup {minus}3}, confirmed by Hall effect measurements. The residual donors have been analyzed by far infrared spectroscopy and found to be sulfur and silicon. Epilayers with thicknesses of up to 120 {micro}m have been deposited on 650 {micro}m thick semi-insulating GaAs substrates and on 500 {micro}m thick n{sup +}-type GaAs substrates. The authors report the results obtained with Schottky barrier diodes fabricated from these high purity n-type GaAs epilayers and operated as X-ray detectors. The Schottky barrier contacts consisted of evaporated circular gold contacts on epilayers on n{sup +} substrates. The ohmic contacts were formed by evaporated and alloyed Ni-Ge-Au films on the back of the substrate. Several of the diodes exhibit currents of the order of 1 to 10 nA at reverse biases depleting approximately 50 {micro}m of the epilayer. This very encouraging result, demonstrating the possibility for fabricating GaAs p-i-n diodes with depletion layers in high purity GaAs instead of semi-insulating GaAs, is supported by similar results obtained by several other groups. The consequences of using high purity instead of semi-insulating GaAs will be much reduced charge carrier trapping. Diode electrical characteristics and detector performance results using {sup 55}Fe and {sup 241}Am radiation will be discussed.
- Sponsoring Organization:
- National Aeronautics and Space Administration, Washington, DC (United States); USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 323882
- Report Number(s):
- CONF-971201-; TRN: 99:004414
- Resource Relation:
- Conference: 1997 fall meeting of the Materials Research Society, Boston, MA (United States), 1-5 Dec 1997; Other Information: PBD: 1998; Related Information: Is Part Of Semiconductors for room-temperature radiation detector applications 2; James, R.B. [ed.] [Sandia National Labs., Livermore, CA (United States)]; Schlesinger, T.E. [ed.] [Carnegie Mellon Univ., Pittsburgh, PA (United States)]; Siffert, P. [ed.] [Lab. PHASE/CNRS, Strasbourg (France)]; Dusi, W. [ed.] [Inst. TESRE/CNR, Bologna (Italy)]; Squillante, M.R. [ed.] [Radiation Monitoring Devices, Inc., Watertown, MA (United States)]; O`Connell, M. [ed.] [Dept. of Energy, Washington, DC (United States)]; Cuzin, M. [ed.] [LETI/CEA, Grenoble (France)]; PB: 681 p.; Materials Research Society symposium proceedings, Volume 487
- Country of Publication:
- United States
- Language:
- English
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