TY - JOUR
T1 - Substrate effect on the electrical properties of a-Si:H thin films and its modification by diffusion-blocking interlayers
AU - Bregman, J.
AU - Gordon, J.
AU - Shapira, Yoram
AU - Fortunato, E.
AU - Martins, R.
AU - Guimaraes, L.
N1 - Funding Information:
a ‐Si:H thin films Bregman J. Gordon J. Shapira Yoram Faculty of Engineering, Tel Aviv University, Ramat Aviv 69978, Israel Fortunato E. Martins R. Guimaraes L. Faculdade Ciencias e Tecnologia, Universidade Nova de Lisboa (D.C.M.) and Centro Fisica Molecular das U. L. (I.N.I.C.), 1000‐Lisboa, Portugal 07 1989 7 4 2628 2631 27 October 1988 4 February 1989 1989 American Vacuum Society Electrical dark conductivity (σ d ) and surface composition of undoped and doped a ‐Si:H thin films have been investigated, using coplanar I – V measurements as a function of temperature and Auger electron spectroscopy (AES). The films were prepared by rf glow discharge deposition on standard soda‐lime glass and on alkali‐free glass substrates. Comparing these two sets of substrates for undoped films, we find that σ d of the films deposited on soda‐lime glass substrates at room temperature is higher by more than two orders of magnitude, their activation energy is lower by about a factor of 3, and their photosensitivity (σ ph /σ d ) is lower by two orders of magnitude than that of the films deposited on alkali‐free glass substrates. We suggest that Na ions, leached from the glass into the a ‐Si:H overlayer play a significant role in determining the film conductivity by creating electrically active donorlike states. This conclusion is supported by similar measurements on p ‐ and n ‐type a ‐Si:H films on the same substrates and by AES results. Films of a ‐Si:H, grown on thin a ‐Si:C:H interlayers on soda‐lime glass, showed very low Na concentrations and low dark conductivities as found by AES and electrical measurements, respectively. The role of the a ‐Si:C:H interlayers as diffusion barriers is discussed. SILICON AMORPHOUS STATE HYDROGENATION THIN FILMS ELECTRICAL PROPERTIES IV CHARACTERISTIC TEMPERATURE DEPENDENCE AUGER ELECTRON SPECTROSCOPY CHEMICAL COMPOSITION SODA−LIME GLASSES SUBSTRATES COATINGS INTERFACES DARK CONDUCTIVITY BORON ADDITIONS PHOSPHORUS ADDITIONS DEPOSITION GLOW DISCHARGES (Si,H)
PY - 1989/7
Y1 - 1989/7
N2 - Electrical dark conductivity (σd) and surface composition of undoped and doped a-Si:H thin films have been investigated, using coplanar I−V as a function of temperature and Auger electron spectroscopy (AES). The films were prepared by rf glow discharge deposition on standard soda-lime glass and on alkali-free glass substrates. Comparing these two sets of substrates for undoped films, we find that σd of the films deposited on soda-lime glass substrates at room temperature is higher by more than two orders of magnitude, their activation energy is lower by about a factor of 3, and their photosensitivity (σph/σd) is lower by two orders of magnitude than that of the films deposited on alkali-free glass substrates. We suggest that Na ions, leached from the glass into the a-Si:H overlayer play a significant role in determining the film conductivity by creating electrically active donorlike states. This conclusion is supported by similar measurements on p- and n-type a-Si:H films on the same substrates and by AES results. Films of a-Si:H, grown on thin a-Si:C:H interlayers on soda-lime glass, showed very low Na concentrations and low dark conductivities as found by AES and electrical measurements, respectively. The role of the a-Si:C:H interlayers as diffusion barriers is discussed.
AB - Electrical dark conductivity (σd) and surface composition of undoped and doped a-Si:H thin films have been investigated, using coplanar I−V as a function of temperature and Auger electron spectroscopy (AES). The films were prepared by rf glow discharge deposition on standard soda-lime glass and on alkali-free glass substrates. Comparing these two sets of substrates for undoped films, we find that σd of the films deposited on soda-lime glass substrates at room temperature is higher by more than two orders of magnitude, their activation energy is lower by about a factor of 3, and their photosensitivity (σph/σd) is lower by two orders of magnitude than that of the films deposited on alkali-free glass substrates. We suggest that Na ions, leached from the glass into the a-Si:H overlayer play a significant role in determining the film conductivity by creating electrically active donorlike states. This conclusion is supported by similar measurements on p- and n-type a-Si:H films on the same substrates and by AES results. Films of a-Si:H, grown on thin a-Si:C:H interlayers on soda-lime glass, showed very low Na concentrations and low dark conductivities as found by AES and electrical measurements, respectively. The role of the a-Si:C:H interlayers as diffusion barriers is discussed.
UR - http://www.scopus.com/inward/record.url?scp=80055052298&partnerID=8YFLogxK
U2 - 10.1116/1.575808
DO - 10.1116/1.575808
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AN - SCOPUS:80055052298
SN - 0734-2101
VL - 7
SP - 2628
EP - 2631
JO - Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films
JF - Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films
IS - 4
ER -