Physics of semiconductor power devices

Abstract

Semiconductor power devices are designed to rapidly switch or amplify high currents, to support high voltages, and to control electric power. Because of these requirements, their topographies and structures are different from those of small-signal devices. Specific designs are the result of the understanding of the physics of p-n junction HV breakdown, gain variation at high currents, current instabilities, etc. After introducing elementary semiconductor structures, the article reviews the basic principles of the operation of bipolar and field-effect power transistors and thyristors. This is followed by a discussion of phenomena of special interest for power devices: junction avalanche breakdown, the effect of the current level on the current gain, dynamic and static behaviour at high currents and thermal properties and instabilities. The review includes recent advances in device physics and introduces the reader to new methods of improving device performance. Power is a relative concept-at microwave frequencies a few watts is a very large quantity; this review therefore includes a section on microwave power devices.

Piezo-phototronic Effect Enhanced Responsivity of Photon Sensor Based on Composition-Tunable Ternary CdSxSe1–x Nanowires

“…Usually, the photocurrent depends on the effective separation and transport of both holes and electrons at the vicinity of the contacts and strongly affects the SBH as a result of the TFE theory. 46,47 When tensile strain is applied along the c-axis direction of the semiconductor NW, positive polarization charges were introduced at the vicinity of the source side to reduce the SBH (Φ sT < Φ sL ). The decreasing SBH at local contact will facilitate electron transport across the M−S interface and induce an increasing photocurrent, as shown in Figure 5b.…”

“…The photogenerated electrons in the CB are inclined to move close to the interface of the drain side, and the holes in the VB are inclined to move toward the source side and therefore induce the photocurrent to flow from the drain side to the source. Usually, the photocurrent depends on the effective separation and transport of both holes and electrons at the vicinity of the contacts and strongly affects the SBH as a result of the TFE theory. , …”

Optimization of the window layer in large area silicon heterojunction solar cells

“…The PH 3 /SiH 4 ow ratio was 3% for the a-Si:H buffer layers, while 1.5% for the n-type a-SiO x :H layers. [42][43][44][45][46][47][48][49][50][51] Finally, a total-area conversion efficiency of 21.1% was achieved on 238.85 cm 2 SHJ solar cell when the CO 2 /SiH 4 ow ratio is 0.25. 10 shows the illuminated I-V parameters of solar cells with highly doped a-Si:H buffer layers.…”