Diffusion lengths in solar cells from short-circuit current measurements

Abstract

The minority-carrier diffusion length in the base region of a silicon solar cell has been determined by measuring the short-circuit current as a function of the wavelength of incident light. The incident light intensity required to produce a given short-circuit current is a linear function of the reciprical absorption coefficient for each wavelength, and the extrapolation of this linear relation to zero intensity yields the diffusion length. This method is similar to the surface photovoltage and open-circuit voltage methods; however, the accuracy for high light bias levels appears to be greatly improved.

Physical understanding and technological control of carrier lifetimes in semiconductor materials and devices: A critique of conceptual development, state of the art and applications

“…The intercept of this plot is f1 þ Q s =ðI r t r Þg: Note: Among other methods of recombination lifetime measurement, mention may be made of methods based on: (i) forward diode characteristics [92], (ii) shortcircuit current decay [93,94], (iii) free-carrier absorption [95][96][97] and (iv) electronbeam induced current (EBIC) [98][99][100][101][102].…”

Generalized models of the spectral response of the voltage for the extraction of recombination parameters in silicon devices

“…The simplest model is based on a linearity between the inverse internal quantum efficiency and the penetration depth 1/␣ of light, [11][12][13] …”

Surface photovoltage phenomena: theory, experiment, and applications

“…Thus, diffusion length measurements may be performed using the same setup normally used for spectral response measurements in many solar cell con®gurations. The diffusion length can even be extracted from short-circuit current measurements in a similar manner [444], with an improved linear dependence of the signal on the illumination intensity.…”

“…This is because such measurements potentially enable the extraction of L in the absorber material inside a complete cell structure. Diffusion length values were successfully extracted from open circuit voltage measurements on solar cell junctions [433,443,444,446,449,451,455]. As long as the top region in a homojunction, or the window layer in a heterojunction, are considerably more heavily doped than the absorber (which is usually the case), the depletion region is contained almost entirely within the absorber layer, just like in the case of a free surface or a Schottky contact.…”