What Is DLTS?

An important goal in semiconductor technology is the reduction of intrinsic and process-induced defects in the crystalline, polycrystalline and amorphous layers which comprise all semiconductor devices. Defects arising from impurities, grain boundaries, interfaces, etc. result in the creation of traps which capture free electrons and holes. Even at very low concentrations these trapping centers can dramatically alter device performance.

Deep Level Transient Spectroscopy (DLTS) is an extremely versatile technique for the determination of virtually all parameters associated with traps including density, thermal cross selection, energy level and spacial profile.

By monitoring capacitance or current or charge transients produced by pulsing the semiconductor junction at different temperatures, a spectrum is generated which exhibits a peak for each deep level. The height of the peak is proportional to trap density, its sign allows one to distinguish between minority and majority traps and the position of the peak on the temperature axis leads to the determination of the fundamental parameters governing thermal emission and capture (activation energy and cross section). Application of the method has led to the discovery of new phenomena and has provided a unique tool for the understanding of materials processing for semiconductor devices.

Some Sula DLTS Features: