We report on the atmospheric pressure metalorganic vapour phase epitaxy of both nominally undoped and iodine (I) donor doped CdTe layers on high resistivity (111)B CdTe substrates, as a preliminary step towards the fabrication of p-i-n diode X-ray detectors. CdTe epilayers were grown at 330°C after in-situ H2 heat treatment of the substrate for surface oxide removal. We show that the homoepitaxy of CdTe critically depends on in-situ heat treatment temperature (TA), best epilayer morphology and reduced surface roughness being obtained for TA = 350°C. Secondary ion mass spectrometry analysis of I-doped samples shows good dopant incorporation, which increases for Te:Cd precursor molar flow ratios in the vapour below unity. I-doped samples grown under the latter conditions have room temperature resistivity three orders of magnitude lower than for undoped layers and electron concentrations ~1016 cm-3.
MOVPE growth optimisation of CdTe epitaxial layers for p-i-n diode X-ray detector fabrication
P PRETE;
2006
Abstract
We report on the atmospheric pressure metalorganic vapour phase epitaxy of both nominally undoped and iodine (I) donor doped CdTe layers on high resistivity (111)B CdTe substrates, as a preliminary step towards the fabrication of p-i-n diode X-ray detectors. CdTe epilayers were grown at 330°C after in-situ H2 heat treatment of the substrate for surface oxide removal. We show that the homoepitaxy of CdTe critically depends on in-situ heat treatment temperature (TA), best epilayer morphology and reduced surface roughness being obtained for TA = 350°C. Secondary ion mass spectrometry analysis of I-doped samples shows good dopant incorporation, which increases for Te:Cd precursor molar flow ratios in the vapour below unity. I-doped samples grown under the latter conditions have room temperature resistivity three orders of magnitude lower than for undoped layers and electron concentrations ~1016 cm-3.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
