Speaker
Timo Hannu Tapani Peltola
(Helsinki Institute of Physics (FI))
Description
Radiation detectors made of epitaxial GaAs are an alternative for silicon devices for spectroscopy and radiography applications requiring moderate photon energies more than 10 keV. Being basic starting material of optoelectronics industry, the processing technology of GaAs devices is well established. Atomic numbers (Z=31, 33) of GaAs extends the X-ray absorption edge beyond Si (Z=14) detectors. In this contribution we report processing of 130µm thick epitaxial GaAs pixel detectors fabricated on heavily n-type doped GaAs substrates. An undoped epi layer was grown in a horizontal CVPE reactor. In the final phase of epitaxy, a thin p+ layer doped with zinc was grown to complete the p-i-n structure. The detectors and test structures were characterized by Capacitance Voltage (CV)/ Current Voltage (IV), Transient Current Technique (TCT) and Deep Level Transient Spectroscopy (DLTS) measurements. Full depletion voltage (Vfd) of detectors is about 15V and leakage current at Vfd below 10 nA/cm2 . Signal transit time determined by TCT is about 8ns at bias voltage less than electron drift velocity saturation, which occurs at >30V bias. DLTS measurements revealed deep levels in epitaxial layers. TCAD simulations were carried out with appropriate defect model in order to verify the experimental results.
Co-authors
Mrs
Akiko Gädda
(VTT Microsystem and Nanoelectronics)
Dr
Alexandra Junkes
(Hamburg University (DE))
Aneliya Karadzhinova
(University of Sofia (BG))
Dr
Eija Tuominen
(Helsinki Institute of Physics (FI))
Dr
Esa Veikko Tuovinen
(Helsinki Institute of Physics (FI))
Dr
Jaakko Härkönen
(Helsinki Institute of Physics)
Dr
Panja Luukka
(Helsinki Institute of Physics (FI))
Dr
Pasi Kostamo
(Oxford Instruments Analytical Oy)
Dr
Seppo Nenonen
(Oxford Instruments Analytical Oy)
Timo Hannu Tapani Peltola
(Helsinki Institute of Physics (FI))
Dr
Tommi Riekkinen
(VTT, Microsystem and Nanoelectronics)
