Resonant tunneling in multiple-barrier structures with arbitrary potential profile is studied theoretically. Analytical expressions of the transmission coefficient and the resonance condition are derived by taking into account the mass difference between well and barrier layers. The basic barrier unit in the periodic multiple-barrier structure may be a compound-barrier structure, and the simplest compound-barrier unit is the double-barrier unit. Two independent resonance conditions exist in the multiple-barrier structures with compound-barrier unit and both the subband gap energy and the energy value at the center of the subband gap may be determined analytically and independently for the multiple-barrier structure with doublebarrier unit.

A new design of power supply based on the idea of switched capacitors, as applied to pocket computer systems, is presented. This new type of power supply is inductorless and, consequently, suitable for hybridization and even monolithic integration. The new design is also based on distinguishing characteristics of pocket digital computer systems, in which a switched-capacitor converter can work well, since minimal regulation is required. The new device may enable the pocket computer system to be powered by only one battery, resulting in a simple topology. Two switched-capacitor converters, +12 V/-12 V, +5 V and +5 V/+12 V, -12 V, are shown, respectively, as an example for demonstrating the basic principle and its performance. PSPICE simulation and laboratory models show good results for this new type of power supply.

Optoelectronic characteristies of the SiCl-ZGeZ/SiC heterojunction photodiode are simulated using MEDICI after the theoretical investigation of key properties for SiCl-xGex. The calculations show that SiCl-xGex/SiC with x=0.3 may have a small lattice mismatch with 3C-SiC and a good response to the visible light and the near infrared light. The response spectrum of the SiCl-xGex/SiC heterojunction photodiode, which consists of a p-type SiCl-xGex absorption layer with a doping concentration of 1×1015cm-3 ,a thickness of 1.6μm and x=0.3, has a peak of 250mA/W at 0.52μm and the peak can even reach 102mA/W at 0.7μm.

In this paper, we present a novel method to grow 3C-SiC crystal in a liquid-phase epitaxy-like manner, but without any substantial substrate. The starting material to be used in this method is the 3C-SiC-thin film deposited on Si substrate in a gas-phase heteroepitaxial technology. The free 3C-SiC film which remained of the molten Si substrate epitaxially grows up from the Si solution saturated by SiC in a highly purified graphite crucible heated by an inductive heater. XRD, XPS and Raman spectroscopy were used to characterize the samples. The only one peak with full width at half maximum (FWHM) of 0.2 at 20 = 35.65

A theoretical analysis has been carried out to compare the resonance condition in the asymmetric double-barrier structure with that in the symmetric triple-barrier one. It is. found that. the triple-barrier structure may be considered as two quasidouble-barrier structures whose resonance condition may decide the resonance levels in the triple-barrier structure. It is confirmed that two modes exist in the triple-barrier structure: one is "normal mode consisting of doublet and the other is degenerated mode of singlet. The critical condition between the two modes is given and its physical meaning is examined. Moreover, it is confirmed that both the normal mode and the degenerated mode exist also in symmetric n-fold barrier structures (n≥3).