Abstract

ROSALES-QUINTERO, P. et al. Impact of the base doping concentration on the transport mechanisms in n-type a-SiGe:H/p-type c-Silicon Heterojunctions. Rev. mex. fis. [online]. 2011, vol.57, n.2, pp.133-139. ISSN 0035-001X.

The charge transport mechanisms occurring in n-type a-SiGe:H on p-type c-Si heteroj unctions were determined by analyzing the temperature dependence of the current-voltage characteristics in structures with four different peak base doping concentrations (N_B = 1 x 10¹⁵, 7 x 10¹⁶, 7 x l0¹⁷ and 5 x lO¹⁸ cm^-3). From the experimental results, we observed that at low forward bias (V< 0.45V) the current is determined by electron diffusion from the n-type amorphous film to the p-type c-Si for the heterojunction with N_B = 1 x 10¹⁵cm^-3, whereas the Multi-Tunneling Capture Emission (MTCE) was identified as the main transport mechanism for the other base doping concentrations. On the other hand, at high forward bias (V> 0.45V), the space charge limited current effect became the dominant transport mechanism for all the measured devices. Under reverse bias the transport mechanisms depends on the peak base doping, going from carrier generation inside the space charge region for the lowest doping, to hopping and thermionic field emission as the base doping concentration is increased.

Keywords : Amorphous semiconductors; heterojunction diodes; transport mechanisms; base doping concentration.

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