Processing and characterization of epitaxial GaAs radiation detectors

• DOI: 10.1016/j.nima.2015.03.028
• Publication Date: 2015-03-29T07:15:36Z
• Authors: X. Wu; T. Peltola; T. Arsenovich; A. Gädda; J. Härkönen; A. Junkes; A. Karadzhinova; P. Kostamo; H. Lipsanen; P. Luukka; M. Mattila; S. Nenonen; T. Riekkinen; E. Tuominen; A. Winkler
• Keywords: Defect characterization; Solid state radiation detectors; Physics - Instrumentation and Detectors; ta213; ta114; Wafer processing; GaAs; ta221; FOS: Physical sciences; Instrumentation and Detectors (physics.ins-det); 01 natural sciences; 7. Clean energy; 03 medical and health sciences; TCAD simulations; 0302 clinical medicine; 0103 physical sciences; ta318; ta216; ta116

7 pages, 10 figures, 10th International Conference on Radiation Effects on Semiconductor Materials, Detectors and Devices (RESMDD14), 8-10 October, Firenze, Italy<br/>GaAs devices have relatively high atomic numbers (Z=31, 33) and thus extend the X-ray absorption edge beyond that of Si (Z=14) devices. In this study, radiation detectors were processed on GaAs substrates with 110 $��\textrm{m}$ - 130 $��\textrm{m}$ thick epitaxial absorption volume. Thick undoped and heavily doped p$^+$ epitaxial layers were grown using a custom-made horizontal Chloride Vapor Phase Epitaxy (CVPE) reactor, the growth rate of which was about 10 $��\textrm{m}$/h. The GaAs p$^+$/i/n$^+$ detectors were characterized by Capacitance Voltage ($CV$), Current Voltage ($IV$), Transient Current Technique (TCT) and Deep Level Transient Spectroscopy (DLTS) measurements. The full depletion voltage ($V_{\textrm{fd}}$) of the detectors with 110 $��\textrm{m}$ epi-layer thickness is in the range of 8 V - 15 V and the leakage current density is about 10 nA/cm$^2$. The signal transit time determined by TCT is about 5 ns when the bias voltage is well above the value that produces the peak saturation drift velocity of electrons in GaAs at a given thickness. Numerical simulations with an appropriate defect model agree with the experimental results.<br/>