Ambipolar Phototransport (mu tau e=mu tau h) Observed as an Intrinsic Property of A-SiGe:H

Ambipolar Phototransport (mu tau e=mu tau h) Observed as an Intrinsic Property of A-SiGe:H

Research output: Contribution to conference › Paper

Abstract

A study is presented of a series of high quality PECVD a-Si0.33Ge0.67 films, produced by cathodic deposition, in which small concentrations of PH3, B2H6 or air impurities were added during deposition. The quantum efficiency-mobility-lifetime product increases, and the ambipolar diffusion length (L amb) decreases monotonically with dopant concentration for both PH3 and B2H6. This result is strongevidence that for these films neither photocarrier is dominant at zero doping. This result is very different from what has been typically observed by other researchers, that the electron is the dominant photocarrier for undoped a-SiGe:H. Drive level capacitance (DLC) measurements of these alloys show an unusual behavior of being temperature-independent, and the dark conductivity activationenergy is maximum for zero doping. It is proposed that all of these unusual properties are due to the unusually low impurity concentration of these films, and that these properties are, in fact, the intrinsic properties for a-SiGe:H alloys. To verify this, films were prepared with a calibrated and controlled air leak introduced during deposition. As the air leak was increased, the filmproperties changed to typical behavior. Even for air concentrations as low as 2 ppm (gas phase), the transport measurements showed changes consistent with a shift in the Fermi level toward the conduction band.

Original language	American English
Pages	263-268
Number of pages	6
State	Published - 1997
Event	Amorphous and Microcrystalline Silicon Technology 1997: Materials Research Society Symposium - San Francisco, California Duration: 31 Mar 1997 → 4 Apr 1997

Conference

Conference	Amorphous and Microcrystalline Silicon Technology 1997: Materials Research Society Symposium
City	San Francisco, California
Period	31/03/97 → 4/04/97

Bibliographical note

Work performed by Harvard University, Cambridge, Massachusetts, Boston College, Boston, Massachusetts, University of Oregon, Eugene, Oregon, and Lawrence Livermore National Laboratory, Livermore, California

NREL Publication Number

NREL/CP-520-24551

Cite this

@conference{b076c7b5c3a44ac0b38ad3d2f230c95c,

title = "Ambipolar Phototransport (mu tau e=mu tau h) Observed as an Intrinsic Property of A-SiGe:H",

abstract = "A study is presented of a series of high quality PECVD a-Si0.33Ge0.67 films, produced by cathodic deposition, in which small concentrations of PH3, B2H6 or air impurities were added during deposition. The quantum efficiency-mobility-lifetime product increases, and the ambipolar diffusion length (L amb) decreases monotonically with dopant concentration for both PH3 and B2H6. This result is strongevidence that for these films neither photocarrier is dominant at zero doping. This result is very different from what has been typically observed by other researchers, that the electron is the dominant photocarrier for undoped a-SiGe:H. Drive level capacitance (DLC) measurements of these alloys show an unusual behavior of being temperature-independent, and the dark conductivity activationenergy is maximum for zero doping. It is proposed that all of these unusual properties are due to the unusually low impurity concentration of these films, and that these properties are, in fact, the intrinsic properties for a-SiGe:H alloys. To verify this, films were prepared with a calibrated and controlled air leak introduced during deposition. As the air leak was increased, the filmproperties changed to typical behavior. Even for air concentrations as low as 2 ppm (gas phase), the transport measurements showed changes consistent with a shift in the Fermi level toward the conduction band.",

author = "NREL",

note = "Work performed by Harvard University, Cambridge, Massachusetts, Boston College, Boston, Massachusetts, University of Oregon, Eugene, Oregon, and Lawrence Livermore National Laboratory, Livermore, California; Amorphous and Microcrystalline Silicon Technology 1997: Materials Research Society Symposium ; Conference date: 31-03-1997 Through 04-04-1997",

year = "1997",

language = "American English",

pages = "263--268",

}

TY - CONF

T1 - Ambipolar Phototransport (mu tau e=mu tau h) Observed as an Intrinsic Property of A-SiGe:H

AU - NREL, null

N1 - Work performed by Harvard University, Cambridge, Massachusetts, Boston College, Boston, Massachusetts, University of Oregon, Eugene, Oregon, and Lawrence Livermore National Laboratory, Livermore, California

PY - 1997

Y1 - 1997

N2 - A study is presented of a series of high quality PECVD a-Si0.33Ge0.67 films, produced by cathodic deposition, in which small concentrations of PH3, B2H6 or air impurities were added during deposition. The quantum efficiency-mobility-lifetime product increases, and the ambipolar diffusion length (L amb) decreases monotonically with dopant concentration for both PH3 and B2H6. This result is strongevidence that for these films neither photocarrier is dominant at zero doping. This result is very different from what has been typically observed by other researchers, that the electron is the dominant photocarrier for undoped a-SiGe:H. Drive level capacitance (DLC) measurements of these alloys show an unusual behavior of being temperature-independent, and the dark conductivity activationenergy is maximum for zero doping. It is proposed that all of these unusual properties are due to the unusually low impurity concentration of these films, and that these properties are, in fact, the intrinsic properties for a-SiGe:H alloys. To verify this, films were prepared with a calibrated and controlled air leak introduced during deposition. As the air leak was increased, the filmproperties changed to typical behavior. Even for air concentrations as low as 2 ppm (gas phase), the transport measurements showed changes consistent with a shift in the Fermi level toward the conduction band.

AB - A study is presented of a series of high quality PECVD a-Si0.33Ge0.67 films, produced by cathodic deposition, in which small concentrations of PH3, B2H6 or air impurities were added during deposition. The quantum efficiency-mobility-lifetime product increases, and the ambipolar diffusion length (L amb) decreases monotonically with dopant concentration for both PH3 and B2H6. This result is strongevidence that for these films neither photocarrier is dominant at zero doping. This result is very different from what has been typically observed by other researchers, that the electron is the dominant photocarrier for undoped a-SiGe:H. Drive level capacitance (DLC) measurements of these alloys show an unusual behavior of being temperature-independent, and the dark conductivity activationenergy is maximum for zero doping. It is proposed that all of these unusual properties are due to the unusually low impurity concentration of these films, and that these properties are, in fact, the intrinsic properties for a-SiGe:H alloys. To verify this, films were prepared with a calibrated and controlled air leak introduced during deposition. As the air leak was increased, the filmproperties changed to typical behavior. Even for air concentrations as low as 2 ppm (gas phase), the transport measurements showed changes consistent with a shift in the Fermi level toward the conduction band.

M3 - Paper

SP - 263

EP - 268

T2 - Amorphous and Microcrystalline Silicon Technology 1997: Materials Research Society Symposium

Y2 - 31 March 1997 through 4 April 1997

ER -

Ambipolar Phototransport (mu tau e=mu tau h) Observed as an Intrinsic Property of A-SiGe:H

Abstract

Conference

Bibliographical note

NREL Publication Number

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Cite this