Title :
A MOVPE technology for fabrication of CdTe-based homoepitaxial p-i-n diode structures as nuclear radiation detectors
Author :
Traversa, M. ; Prete, P. ; Farella, I. ; Paiano, P. ; Marzo, F. ; Cola, A. ; Lovergine, N. ; Mancini, A.M.
Author_Institution :
Univ. del Salento, Lecce
Abstract :
The homoepitaxy of n-CdTe:l layers is reported as a technological step towards the fabrication of CdTe-based p-i-n diode nuclear radiation detectors. CdTe:I layers were grown at 330degC on detector-grade (111)-oriented CdTe crystals by metalorganic vapour phase epitaxy. To ensure CdTe homoepitaxy, as-received substrates were treated before growth by etching in Br2-methanol and in-situ H2 heat-cleaning at 350degC. (111)-oriented layers with fairly good surface morphology were obtained on as-prepared substrates by growing under Cd-rich vapour conditions. I-doped samples turned out to be n-type with resistivity values around a few Omega.cm and electron concentration ~1016 cm-3, but substantial electrical compensation of I donors occurs in the material, likely due to the formation of unintentional VCd-lTe acceptor centres. Homoepitaxial n-CdTe:I/i-CdTe samples were used to fabricate a preliminary Pt/i-CdTe/n-CdTe:I/AI device structure. Improvement of electrical insulation between back and front electrodes in this M-i-n device was achieved by reactive ion etching of the CdTe:I layer around the Al electrode. This treatment turned out to be effective in reducing the current flowing through the device under reverse bias conditions by more than one order of magnitude.
Keywords :
cadmium compounds; p-i-n diodes; particle detectors; radiation detection; sputter etching; substrates; surface morphology; vapour phase epitaxial growth; CdTe; MOVPE technology; as-prepared substrates; electrical compensation; electrical insulation; electrodes; electron concentration; heat-cleaning; homoepitaxial p-i-n diode structures; metalorganic vapour phase epitaxy; nuclear radiation detectors; reactive ion etching; reverse bias conditions; surface morphology; Crystals; Electrodes; Epitaxial growth; Epitaxial layers; Etching; Fabrication; P-i-n diodes; Phase detection; Radiation detectors; Substrates;
Conference_Titel :
Advances in Sensors and Interface, 2007. IWASI 2007. 2nd International Workshop on
Conference_Location :
Bari
Print_ISBN :
978-1-4244-1245-7
Electronic_ISBN :
978-1-4244-1245-7
DOI :
10.1109/IWASI.2007.4420028