Scanning electronic microscopy (SEM) was used in this work in order to study the surface quality of Lead Telluride (PbTe), n-type, epitaxial layers, grown directly over single crystal Silicon (Si) p-type wafers. The n-PbTe/p-Si heterojunction is used as thermal infrared (IR) detector, which work at room temperature. Besides the epilayers quality, it was also planned, to improve the cleaning Si surface procedure, decide which substrate resistivity is more appropriated and at what thickness the epilayers absorb more infrared radiation.

Study of PbTe Epitaxial Layers Grown Directly Over Silicon Wafers

: This work is to present results of flash evaporation of PbTe directly over single crystals p-type Si substrates, in order to produce heterojunction infrared detectors (HIRD), working at 4.3 micrometers IR wavelength. The evaporation was performed on modified JEOL vacuum equipment, model JEE4B (a), working with vacuum pressure around 10(exp -5) torr, using diffusion pump. The HIRDs produced with this method presented the same detectivity (D*) values of HIRDs made with Hot Wall Epitaxial System (HWE) (b), in which PbTe epitaxial layers were grown directly over the same Si substrates, where an ionic pump reached about 10(exp -9) torr as vacuum pressure. The best results. were obtained with PbTe layers grown with Molecular Beam Epitaxial (MBE) method (c) directly over Si substrates, where the vacuum pressure is around 10(exp -9) torr, also using an ionic pump. The advantage of growing PbTe directly over Si wafers is that the HIRDs perform at room temperature. The detectivity values of HIRDs obtained with methods (a) and (b), were D* approx. 4, 8 x 10(exp 5) cm.Hz(sup 1/2)/W and with method (c), D* approx. 6, 7 x 10(exp 6) cm.Hz(sup 1/2/W. Different technologies: (a) very low costs, (c) high technology; not very different results.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S194642740062451X

Sabrina de Castro Ferreira Ferraz da Silva

Papers

Study of PbTe Epitaxial Layers Grown Directly Over Silicon Wafers

PbTe Flash Evaporation on Si Substrates for Heterojunction Infrared Detectors