ELECTRONIC CONDUCTIVITY OF HYDROGENATED NANOCRYSTALLINE SILICON FILMS

A heteroquantum‐dots (HQD) model for hydrogenated nanocrystalline silicon films (nc‐Si:H) is proposed. The main features of our model are as follows. (i) the nanocrystalline grains and the amorphous counterparts in which they are embedded have very different band gap and band structures. As a result, they form heterojunctionlike structures in the interface regions, where the band offset effects dramatically reduce the activation energy and the grains act like quantum dots. (ii) In the presence of an external field, the activated electrons in the quantum dots conduct via quantum tunneling through the interface barriers. By means of the HQD model, we have identified the conduction of nc‐Si:H as a thermal‐assisted tunneling process. Our results show that there are two distinct regimes for the conductivity of nc‐Si:H: (i) the low‐temperature regime, where there is a simple activation energy ΔE; (ii) the high‐temperature regime, where ΔE is effectively enhanced by the temperature effect of the electronic tunne...

[1]  Giorgio Baccarani,et al.  Transport properties of polycrystalline silicon films , 1978 .

[2]  J. Seto.  The electrical properties of polycrystalline silicon films , 1975 .

[3]  Michel Devoret,et al.  Single Charge Tunneling , 1992 .

[4]  R. A. Webb,et al.  Mesoscopic phenomena in solids , 1991 .

[5]  L. Canham.  Silicon quantum wire array fabrication by electrochemical and chemical dissolution of wafers , 1990 .

[6]  M. Konuma,et al.  Dependence of electrical conductivity of nanocrystalline silicon on structural properties and the effect of substrate bias , 1987 .

[7]  U. Merkt.  Quantum dots on indium antionide , 1990 .

[8]  F. Evangelisti.  Photoemission studies of amorphous semiconductor heterojunctions , 1985 .

[9]  Zafar Iqbal,et al.  Raman scattering from hydrogenated microcrystalline and amorphous silicon , 1982 .

[10]  R. Street,et al.  Hydrogenated amorphous silicon: Index , 1991 .

[11]  H. Grabert,et al.  Special issue on single charge tunneling , 1991 .

[12]  Y. L. He,et al.  Transient and steady-state optoelectronic properties of μc-Si:H , 1991 .

[13]  Ye,et al.  Resonant tunneling via microcrystalline-silicon quantum confinement. , 1991, Physical review. B, Condensed matter.

[14]  W. Spear,et al.  Some new results on transport and density of state distribution in glow discharge microcrystalline silicon , 1983 .

[15]  Y. Xie,et al.  Light Emission from Silicon , 1993, Science.

[16]  Lee,et al.  ac conduction and 1/f noise in a Cr-film lattice-percolation system. , 1992, Physical review. B, Condensed matter.

[17]  Fisk,et al.  Observation of velocity-tuned resonances in the reflection of atoms from an evanescent light grating. , 1994, Physical review. A, Atomic, molecular, and optical physics.

[18]  T. Smith.  Quantum confinement in few-electron systems , 1990 .

[19]  Raphael Tsu,et al.  Transport in nanoscale silicon clusters , 1993 .

[20]  Yuliang He,et al.  The structure and properties of nanosize crystalline silicon films , 1994 .

[21]  Cleland,et al.  Influence of the environment on the Coulomb blockade in submicrometer normal-metal tunnel junctions. , 1992, Physical review. B, Condensed matter.

[22]  Yuliang L. He,et al.  Microstructure and Electron Conduction Mechanism of Hydrogenated Nano-crystalline Silicon Films , 1993 .

[23]  Qiliang Li,et al.  Microstructures and characteristics of nano-size crystalline silicon films , 1992 .

[24]  Y. Marfaing,et al.  Study of the band discontinuities at the a-SiH/c-Si interface by internal photoemission , 1985 .