Gallium arsenide photodetectors for imaging in the far ultraviolet region

The aim of the present work is to systematically investigate the response and stability of commercial GaAs devices in the 200–400 nm UV range with a view to establishing their potentiality in imaging devices. The irradiation results of GaAs detectors with various geometries are presented and discussed. The detectors were reverse biased in fully depleted condition and in partially depleted condition (5 V reverse bias) in order to investigate the possibilities of integration with the standard bias values of read-out-integrated circuits. The results show that fabrication technology for nondedicated devices is still immature

Investigation of compensation defect centres in semi-insulating InP crystals

Laplace transform photoinduced transient spectroscopy (LTPITS) has been applied to study defect centres in Fe-doped and undoped semi-insulating (SI) InP. A high resistivity (~ 2 × 107 Ω cm) of the latter was achieved by annealing at 950 °C for 40 h under a phosphorus overpressure. It is shown that shallow donors in this material have an activation energy of 10 meV and are mainly compensated with deep acceptors characterised by activation energies of 350 and 470 meV with respect to the bottom of the conduction band. In the Fe-doped material, the shallow donors are compensated with Fe-related deep acceptors having activation energies of 590 and 640 meV

On the electrical and detection performances of particle detectors based on bulk semi-insulating InP

A study of electrical transport and detection performances of the bulk semi-insulating InP-based detectors of charged particles and γ rays is presented. The best detectors give a charge collection efficiency over 90% and energy resolution about 3% (FWHM) for 5.48 MeV α-particles and an energy resolution about 7% (FWHM) for 122 keV γ-rays at 220 K. Detection performances versus temperature, contact systems and bias voltage polarity have been discussed

Semi-insulating InP particle detectors for X- and γ-ray detection

A study of electrical properties and detection performances of the semi-insulating (SI) InP based detectors is presented. Detectors with a top P+ layer and a Schottky back contact give the charge collection efficiency about 90% and an energy resolution 3.7% (FWHM) for 5.48 MeV α-particles at 250 K. Detection of X-rays (122 keV and 60 keV) photons in temperature region 220-250 K is demonstrated. Multiple peaking observed during detection of photons is discussed

X- and gamma-ray detectors based on bulk semi-insulating GaAs & InP: Present status and prospects

In this work, the different aspects of X-ray digital radiology are considered and the requirements of the materials for radiation detector applications are identified. The status of development of X- and gamma/-ray detectors based on semi-insulating (SI) GaAs and InP is reviewed. Emphasis is put on the (i) basic material characteristics, (ii) role of the electrodes in the overall detector performances. Detectors recently developed at IEE SAS are illustrated along with the first digital images taken with the detectors. Some conclusions about the relationship between material quality and applications are provided