Spatial dependence of the carrier lifetime in thin films of silicon on sapphire

Abstract

An experimental technique is described for determination of the generation carrier lifetime as a function of the distance of the insulator-semiconductor interface. This method is applied to thin films of silicon on sapphire nominally 1 μ thick and doped n type.

The Properties of Silicon-on-Sapphire Substrates, Devices, and Integrated Circuits

“…This structure can be used to measure the carrier lifetime as a function of distance from the silicon-silicon dioxide surface. The lifetime was also shown by Schroder 63 and Kranzer 64 to decrease with increasing film doping concentration as evidenced in bulk silicon. 25.…”

“…Using this structure, Kranzer 64 showed that the carrier lifetime decreases monatonically with depth into the SOS film as shown in Fig. This structure can be used to measure the carrier lifetime as a function of distance from the silicon-silicon dioxide surface.…”

“…168 Based on the work of Kennedy and Phillips, 169 they proposed the existence of a thin film bipolar transistor as shown in Fig. It should be noted that the lifetime decreases significantly with distance away from the silicon-dioxide surface 64 and, therefore, the average lifetime may be significantly less than a nanosecond in the base region. The substrate represents the base of the bipolar device, while the source and drain are the corresponding emitter and collector.…”

Large thickness-dependent improvement of crystallographic texture of CVD silicon films on R-sapphire

“…The stress in SOS films was characterized by Raman spectroscopy [16], giving the values of 7.0±0.3 kbar at room temperature and 8.7±0.3 kbar at 77 K for films with thickness of 0.6Ͳ0.9 ʅm. The electrophysical properties of SOS films were studied as well [17], [18]. It was shown that the average carrier mobility and normalized impurity concentration are gradually decreasing functions of position within the film, with the maximum mobility observed on the film surface and the minimum mobility values found on the Si interface with the sapphire substrate.…”

Full CVD Reel‐To‐Reel Process to Obtain Perfectly Oriented Silicon Films on Metal Tapes with Oxide Buffer Layers**

“…The competition between film texture and stress is of great interest as both factors have a crucial effect on semiconductor electric properties. [13,14] Further characterization of charge-carrier lifetime and mobility properties of films should be carried out.…”