IBIC analysis of gallium arsenide Schottky diodes

Citation
E. Vittone et al., IBIC analysis of gallium arsenide Schottky diodes, NUCL INST B, 158(1-4), 1999, pp. 470-475
Citations number
9
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Spectroscopy /Instrumentation/Analytical Sciences","Instrumentation & Measurement
Journal title
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS
ISSN journal
0168-583X → ACNP
Volume
158
Issue
1-4
Year of publication
1999
Pages
470 - 475
Database
ISI
SICI code
0168-583X(199909)158:1-4<470:IAOGAS>2.0.ZU;2-V
Abstract
Semi-insulating (SI) gallium arsenide (GaAs) devices operating as a reverse biased Schottky diode offer an attractive choice as radiation detector at room temperature both in high energy physics experiments and as X-ray image sensors. However, SI GaAs devices contain a high concentration of traps, w hich decreases the charge collection efficiency (cce), and affects the ener gy resolution of such detectors working as nuclear spectrometers. In this p aper we present a detailed investigation of the spatial uniformity of the c ce carried out by analysing ion beam induced charge (IBIC) space maps obtai ned by scanning a focused 2 MeV proton microbeam on a SI n-GaAs Schottky di ode. The microbeam irradiated both the front (Schottky) and back (ohmic) co ntacts in order to evaluate the transport properties of both electrons and holes generated by ionisation, The IBIC space maps show a clear non-uniform ity of the cce. The poor energy resolution previously observed in such dete ctors working as alpha particle spectrometers is ascribed to the presence o f two different "phases" in the material, which produce two distinct collec tion efficiency spectra. Such ''phases" show different behaviour as a funct ion of the applied bias voltage which is most likely due to the different e lectric field dependence of the relevant capture cross sections of the trap ping centres for both charge carriers. (C) 1999 Elsevier Science B.V. All r ights reserved.