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Thin epitaxial n‐PbTe films of various thicknesses are grown on KCl substrates by hot wall epitaxy (HWE) technique. The X‐ray, SEM and TEM studies of these films revealed their single‐crystalline nature. The Hall mobility (μH) of these films is measured by Van der Pauw technique and compared with the numerically calculated values for PbTe. It is observed that μH very strongly depends on thickness for thin films but becomes independent of film thickness beyond 5 μm approaching its bulk value. The constant value of Hall coefficient in the temperature range 77 to 300 K show the extrinsic nature of these films. It is also noticed that the rate of increase of mobility with decreasing temperature becomes higher with film thickness. The diffused scattering mobility due to the size effect is calculated and compared with experimental data. A large discrepancy observed between these two is explained on the basis of the residual mobility contribution. The residual mobility is attributed to overall scattering due to grain boundaries, dislocations, defects, cleavage steps, and other surface effects.

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& 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 a t the junction. Assuming V & = 540 mV, an energy band diagram for this structure is constructed based on the experimental results. The band discontinuities AE, and AE, are found to be 240 and 530 meV, respectively. Mit der ,,hot-wall"-Epitaxie wird eine anisotype PbTe/Si-Heterostruktur durch eine n-leitende PbTe-Schicht auf einem p-leitendem Siliziumsubstrat realisiert. I-Uund C-U-Charakteristiken dieser Strukturen werden untersucht. Die effektive Diffusionsspannung 7; uber dem pn-ubergang, die aus I-U-Messungen (540 mV) bestimmt wird, stimmt mit dem Wert aus C-U-Messungen (500 mV) uberein. Jedoch ist dieser Wert etwas groBer als der theoretische Wert fur einen idealen Heteroubergang (390 mV). Diese Diskrepanz wird Grenzfliicheneinflussen infolge von Gitterfehlanpassung am ubergang zugeschrieben. Unter der Annahme von V d = 540 mV wird ein Energiebanderdiagramm fur diese Struktur konstruiert, das auf den experimentellen Ergebnissen beruht. Die Biinderdiskontinuititen AEc und AEv werden zu 240 bzw. 530 meV bestimmt.

The dielectric properties of Zn3P2 crystals are measured in the frequency range 103 to 105 Hz and in the temperature region 300 to 493 K. Samples are prepared by the carbon reduction of zinc orthophosphate. The dielectric dispersion at room temperature and at higher temperatures is attributed to space charge polarisation. An attempt is made to analyse the data.

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