Microsecond carrier lifetime measurements in silicon via quasi-steady-state photoluminescence

Modulated quasi-steady-state photoluminescence is used in photovoltaics in order to measure the injection-dependent effective minority carrier lifetime of silicon wafers. In spite of the very advantageous properties of this measurement technique, its wide dissemination in photovoltaics has been hampered so far because of a relatively poor sensitivity limit in terms of carrier lifetime. A systematic analysis of the sensitivity-limiting mechanisms led to a substantial upgrade of sensitivity, tackling the range of effective lifetimes of 1s. This paper discusses the requirements to reach this level of sensitivity. Most prominently, the dependence of a silicon photodiode's response time with respect to the wavelength of the detected light is addressed. As an alternative, InGaAs photodiodes are implemented. The sensitivity of this method with respect to carrier lifetime is evaluated.