Lifetime is a property of a bulk semiconductor material, telling the amout of time, on average, an excess carrier exists in a semiconductor material before recombining to achieve equilibrium. The same parameter is also called “minority carrier lifetime,” “carrier lifetime,” and “recombination lifetime.” Lifetime of a semiconductor with a perfect crystal lattice and no comtamination will be long, and any imperfections in the semiconductor material or contamination will reduce the lifetime. Thus, monitoring lifetime is an excellent method to detect contamination.
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The most common way of measuring lifetime is via a technique called microwave PCD. Many Semilab products include microwave PCD measurement technology. The WT-2000PV offers lifetime measurement and mapping for PV wafers and cells. The WT-1000 offers measurements of lifetime at a single point on a wafer, and the WT-1000b offers measurement of lifetime of large pieces of silicon, via a hand-held probe. The WT-2000P and WT-2000D offer lifetime measurements, via line scans and maps, of blocks and ingots.
Technical Note #200 explains the theory of microwave PCD measurements of lifetime.
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