AlGaAs/GaAs avalanche detector array-1 GBit/s X-ray receiver for timing measurements
- Resource Type
- Periodical
- Authors
- Lauter, J.; Forster, A.; Luth, H.; Muller, K.D.; Reinartz, R.
- Source
- IEEE Transactions on Nuclear Science IEEE Trans. Nucl. Sci. Nuclear Science, IEEE Transactions on. 43(3):1446-1451 Jun, 1996
- Subject
- Nuclear Engineering
Bioengineering
Gallium arsenide
X-ray detection
X-ray detectors
Sensor arrays
Molecular beam epitaxial growth
Aluminum
Avalanche photodiodes
Electromagnetic wave absorption
Dark current
Density measurement
- Language
- ISSN
- 0018-9499
1558-1578
We report on the first realization of 2/spl times/2 detector arrays based on aluminum gallium arsenide/gallium arsenide (AlGaAs/GaAs) heterostructure avalanche photodiodes. These structures consists of a GaAs absorption layer and an AlGaAs/GaAs avalanche layer which acts as a multiplication region. The samples were grown by molecular beam epitaxy (MBE) and processed into pin diodes of different diameters. Dark current densities were as low as 200 pA/mm/sup 2/ at 90% of the breakdown voltage as determined by I-V measurements. The avalanche gain of the devices have been measured with optical pulses. Gains up to a factor of M=1000 have been determined before breakdown. Additionally the excess noise factor F(M) has been derived for gains between M=1 and M=300. The ionization rates ratio of the structure is k=/spl alpha///spl beta/=3.4/spl plusmn/0.3. In connection to a fast electronic readout chain, the time response of the detectors to 14.4 keV X-ray photons has been tested at the ESRF (Grenoble). The time resolution was found to be 200 ps (FWHM) using standard timing electronics.