Ambipolar diffusion length measurements in hydrogenated amorphous silicon

Abstract

State distribution and ambipolar diffusion length in ntype hydrogenated amorphous silicon

Surface photovoltage phenomena: theory, experiment, and applications

“…This is because of the immunity of SSPG to electric ®eld effects. This call was answered by Balberg et al [481]. They concluded that SPV measurements do not yield the true L a , but rather a quantity which depends on it in a non-trivial manner.…”

Steady-state photocarrier grating method of determining electronic states parameters in amorphous semiconductors

“…Some of the results are shown in Figs. [3][4][5][6][7][8][9]. The values of l e = 0.13 AE 10 À2 m 2 (V s) À1 , l h = 10 À4 m 2 (V s) À1 [16] and T = 293 K has been assumed.…”

“…One of the most promising methods of determining the values of diffusion length of carriers in amorphous semiconductors is based on the steady-state photocarrier grating (SSPG) model [1][2][3][4][5][6][7][8][9][10][11][12]. This technique uses an interference pattern obtained over the illuminated sample surface when two coherent radiation beams hit the sample at different angles of incidence (Fig.…”

“…In this case, the electric conductivity r incoh of the sample is simply represented by its photoconductivity evoked by the sum (I 1 + I 2 ) of the intensities of light in the beams incident upon the sample. The ratio r coh /r incoh of the conductivities of the sample with and without the interference of radiation incident upon the sample depends on the carrier diffusion length in a relatively simple way [1,3,5]. In so-called BalbergÕs plot (see e.g., [5]) the linear fitting of 1/K 2 vs. [2/(1 À b)] 1/2 (where K is the grating period, b represents the so-called experimental ratio of photoconductivities) allows one to determine implicitly the carrier diffusion length.…”

“…The ratio r coh /r incoh of the conductivities of the sample with and without the interference of radiation incident upon the sample depends on the carrier diffusion length in a relatively simple way [1,3,5]. In so-called BalbergÕs plot (see e.g., [5]) the linear fitting of 1/K 2 vs. [2/(1 À b)] 1/2 (where K is the grating period, b represents the so-called experimental ratio of photoconductivities) allows one to determine implicitly the carrier diffusion length. However, the surface recombination [12] as well as the non-ambipolar transport of carriers [10] makes the shape of the theoretical dependence in so-called BalbergÕs plot non-linear.…”