Study on n-PbTe/p-Si Heterostructures

An anisotype heterostructure of PbTe/Si is realised by growing n-type PbTe film on a p-type silicon substrate by hot wall epitaxy technique. I-U and C-U characteristics of this structure are studied. The effective built-in potential, V'd, across the junction, determined by the I-U measurements (540 mV) fairly agrees with the value obtained by C-U measurements (500 mV). However this value is somewhat larger than the theoretical value for an ideal heterojunction (390 mV). This discrepancy is attributed to interface effects due to lattice mismatch at the junction. Assuming V'd = 540 mV, an energy band diagram for this structure is constructed based on the experimental results. The band discontinuities ΔEc and ΔEv are found to be 240 and 530 meV, respectively.