Amorphous silicon

About: Amorphous silicon is a research topic. Over the lifetime, 26777 publications have been published within this topic receiving 423234 citations.

Mechanisms of thermal equilibration in doped amorphous silicon

Abstract: Experimental and theoretical investigations of the mechanisms of thermal equilibration in n-type amorphous silicon are presented. The time, temperature, and doping dependence of the band-tail electron density is obtained from sweep-out experiments, and the dangling-bond and donor densities from photothermal deflection spectroscopy (PDS), bias annealing, and C-V characteristic measurements. An important new result is that donors participate in the equilibration, and that the doping efficiency can be greatly enhanced by a depletion bias. Numerical modeling of the transport allows us to deduce the changes in the density of states and in the position of the Fermi energy, both in equilibrium and in the frozen-in state. The equilibrium state is derived by minimizing the free energy of the doped a-Si:H using a simple density-of-states model. With this approach, the electronic properties (doping efficiency, conductivity, Fermi energy, etc.) can be computed and are shown to be in fairly good agreement with all the experimental results, although the observed lack of temperature dependence of the dangling-bond density remains a puzzle. Further evidence is presented that hydrogen motion is the underlying mechanism of equilibration, and we develop a qualitative model to describe the bonding and movement of hydrogen, based on a distribution of weak Si-Si bonds.

Amorphous silicon-silicon nitride thin-film transistors

Abstract: A thin‐film field‐effect transistor has been fabricated using glow‐discharge amorphous silicon as the semiconductor and silicon nitride as the insulator. The transistor operates in the electron (n type) accumulation mode and by changing the gate potential from zero to only 3 V a change in the source‐drain conductance of greater than four orders of magnitude is obtained. The results imply upper limits to the density of gap states in amorphous silicon and interface states at the amorphous silicon‐silicon nitride interface of 3×1016 cm−3 eV−1 and 5×1011 cm−2 eV−1, respectively.

Application of hydrogenated amorphous silicon oxide layers to c-Si heterojunction solar cells

Abstract: Wide-gap hydrogenated amorphous silicon oxide (a-SiO:H), fabricated by plasma process using SiH4 and CO2 gas mixture, has been applied to crystalline silicon (c-Si) heterojunction solar cells It has been demonstrated that incorporation of an a-SiO:H p layer, instead of a hydrogenated amorphous silicon (a-Si:H) p layer, improves the conversion efficiency slightly Moreover, when an a-SiO:H i layer is formed on the c-Si substrate, Si epitaxial growth that occurs at an a-Si:H∕c-Si heterointerface at high deposition temperatures can be prevented entirely Accordingly, high-efficiency solar cells are fabricated more easily by applying a-SiO:H p-i layers to n-type c-Si heterojunction solar cells