The investigation of custom grown vertical zone melt semi-insulating bulk gallium arsenide as a radiation spectrometer

Author

McGregor, D.S. ; Antolak, A.J. ; Chui, H.C. ; Cross, E.S. ; Fang, Z.-Q. ; Flatley, J.E. ; Goorsky, M.S. ; Henry, R.L. ; James, R.B. ; Look, D.C. ; Mier, M.G. ; Morse, D.H. ; Nordquist, P.E.R. ; Olsen, R.W. ; Pocha, M. ; Schieber, M. ; Schlesinger, T.E. ;

Author_Institution

Sandia Nat. Labs., Livermore, CA, USA

Volume

43

Issue

3

fYear

1996

fDate

6/1/1996 12:00:00 AM

Firstpage

1397

Lastpage

1406

Abstract

Vertical zone melt (VZM) bulk GaAs boules have been zone refined (ZR) and zone leveled (ZL) to reduce EL2 deep donor levels and impurity concentrations with the intent of improving properties for gamma ray detectors. ZR and ZL GaAs boules had background impurity levels and deep donor EL2 concentrations near or below detectable limits. The crystal mosaic of the material at locations near the seed end was slightly superior to commercial liquid encapsulated Czochralski (LEC) material, and nearly equivalent to commercial vertical gradient freeze (VGF) material. The crystal mosaic in ZL material degraded towards the tail end. The homogeneity of the electrical properties for the ZL and ZR VZM material was inferior compared to commercially available bulk GaAs material. Post growth annealing may help to homogenize some electrical properties of the material. The charge collection efficiency of the ZR GaAs detectors was only 30% maximum, and only 25% maximum for the ZL GaAs detectors. Resulting gamma ray spectra was poor from detectors fabricated with the ZL or ZR VZM material. Detectors fabricated from material that was both ZR and ZL did not demonstrate gamma ray resolution, and operated mainly as counters. The poor spectroscopic performance is presently attributed to the inhomogeneity of the electrical properties of the ZR and ZL GaAs materials. Comparisons are made with detectors fabricated from VGF SI bulk GaAs

Keywords

III-V semiconductors; carrier mobility; gallium arsenide; gamma-ray detection; gamma-ray spectrometers; impurity states; semiconductor counters; zone refining; 25 to 30 percent; EL2 deep donor levels; GaAs; bulk GaAs boules; charge collection efficiency; crystal mosaic; electrical properties; gamma ray detectors; impurity concentrations; post growth annealing; radiation spectrometer; spectroscopic performance; vertical zone melt semiinsulating bulk GaAs; zone leveled; zone refined; Annealing; Counting circuits; Crystalline materials; Degradation; Gallium arsenide; Gamma ray detection; Gamma ray detectors; Impurities; Tail; Zirconium;

fLanguage

English

Journal_Title

Nuclear Science, IEEE Transactions on

Publisher

ieee

ISSN

0018-9499

Type

jour

DOI

10.1109/23.507073

Filename

507073