Forward-bias capacitance and current measurements for determining lifetimes and band narrowing in p-n junction solar cellsA new method is described and illustrated for determining the minority-carrier diffusion length and lifetime in the base region of p-n junction solar cells. The method requires only capacitance measurements at the device terminals and its accuracy is estimated to be + or - 5%. It is applied to a set of silicon p-n junction devices and the values of the diffusion lengths agree with those obtained using the current response to X-ray excitation but disagree with those obtained by the OCVD method. The reasons for the relative inaccuracy of OCVD applied to silicon devices are discussed. The capacitance method includes corrections for a two-dimensional fringing effects which occur in small area devices. For a device having highly-doped base region and surface (emitter) layer, the method can be extended to enable the determination of material properties of the degenerately doped surface layer. These material properties include the phenomenological emitter lifetime and a measure of the energy band-gap narrowing in the emitter. An alternate method for determining the energy band-gap narrowing from temperature dependence of emitter current is discussed and demonstrated.
Document ID
19790056877
Acquisition Source
Legacy CDMS
Document Type
Conference Proceedings
Authors
Neugroschel, A. (Florida Univ. Gainesville, FL, United States)
Chen, P. J. (Florida Univ. Gainesville, FL, United States)
Pao, S. C. (Florida Univ. Gainesville, FL, United States)
Lindholm, F. A. (Florida, University Gainesville, Fla., United States)