Figure 4: Application examples for Si modulation doping.
From: Modulation Doping of Silicon using Aluminium-induced Acceptor States in Silicon Dioxide
(a,c) Undoped Si fin-FETs can be provided with holes as majority carriers from Al acceptors in the buried oxide layer forming the base of the fin (a), eliminating any size limit due to conventional doping. The band diagram of such fin-FET (c) shows its working principle as hole depletion (p self-conducting) transistor. (b,d) HIT Si solar cells can be equipped with massively enhanced hole contacts where SiO2 is the optimum choice in terms of chemical bond interface passivation (b). Moreover, SiO2 provides a much increased minority (electron) barrier while accelerating holes through a low tunnelling barrier thanks to negatively charged acceptors located about 0.5 eV below the valence band of c-Si. The band diagram of such a hole contact shows its working principle to provide much increased conversion efficiencies of HIT solar cells (d).
