Volume 85, Issue 8, 15 April 1999
Index of content:
85(1999); http://dx.doi.org/10.1063/1.370339View Description Hide Description
A theory of a nonlinear pyroelectric effect in a phase transition region of a ferroelectric thin film due to harmonic temperature changes with large amplitudes reaching tens of K has been developed. Polarization during the temperature cycle–pyroelectric hysteresis loop is obtained at various frequencies, amplitudes, thermal, and electric relaxation times. It is proved that ferroelectricfilm can be maintained in a monodomain state during the cycle. Applicability of a nonlinear pyroelectric cycle to solar energy conversion (ferroelectricsolar cell) is discussed.
85(1999); http://dx.doi.org/10.1063/1.370340View Description Hide Description
The current–voltage characteristics of a doped weakly coupled GaAs/AlAs superlattice(SL) with narrow barriers are measured under hydrostatic pressure from 1 bar to 13.5 kbar at both 77 and 300 K. The experimental results show that, contrary to the results in SL with wide barriers, the plateau in the curve at 77 K does not shrink with increasing pressure, and becomes wider after 10.5 kbar. It is explained by the fact that the resonance peak is higher than the resonance peak. At 300 K, however, because of the more important contribution of the nonresonant component to the current, the plateau shrinks with increasing pressure.
85(1999); http://dx.doi.org/10.1063/1.370341View Description Hide Description
Amorphous has been grown by plasma assisted anodic oxidation at temperatures The growth kinetics can be explained in terms of a constant current anodization model. Infrared absorption spectroscopy has been used to characterize the transverse and longitudinal optic vibrational modes of the oxide network. Values are displaced with respect to bulk oxide due to geometrical optic effects and plasma induced network structure variation. In relaxed we estimate the mean Ge-O-Ge bridging bond angle to be and the full width at half peak height of the bond angle distribution is Electrical measurements on thin oxide capacitors suggest that in 25 nm oxides there are negative charges cm−2 and negligible interface state densities.