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The pyroelectric effect in a thin film rigidly attached to a thick substrate is discussed and compared to the usual (stress-free) effect. The effects of clamping are negligible for the geometry normally used in pyroelectric detectors in the case of three proper ferroelectric-type pyroelectric materials of practical interest, namely, LiTaO3, Pb5Ge3O11, and Sr0.5Ba0.5Nb2O6. In the case of three wurzite-type (nonferroelectric) pyroelectrics, namely, CdS, CdSe, and ZnO, the pyroelectric effect is drastically reduced by such clamping. Thus the pyroelectric effect in the latter materials appears to be piezoelectric in origin, in contrast to the case of most pyroelectric materials.

Measurements have been made of the temperature dependences of the electrical resistivity and Hall coefficient in samples of n- and p-type silicon having impurity concentrations in the 1018 to 1020 cm−3 range. The resistivity data extend from 4° to 900°K, and the Hall data from 4° to 300°K. The results exhibit two noteworthy features: viz., (1) a hump or maximum in the resistivity vs temperature curves at or slightly below the degeneracy temperature in each sample, which is most pronounced in the least heavily doped samples and gradually fades out as the impurity concentration increases, and (2) an extension of the positive dependence of resistivity on temperature below the hump or degeneracy temperature to surprisingly low temperatures in each sample.

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We propose a general method to obtain high conductivity of either type in wide gap semiconductors where compensation normally limits conductivity of one or both types. We suggest that the successes of Amano et al. and of Nakamura et al. in obtaining more than 1018 cm-3 holes in GaN are particular examples of the general process that we propose.