Density of gap states in hydrogenated amorphous silicon
Amorphous silicon hydride films were grown by an improved rf sputtering method in a hydrogen-argon atmosphere. Deposition parameters such as substrate temperature, gas flow rate, r.f. power and argon partial pressure were kept constant, while hydrogen partial pressure was varied. The infrared vibrational modes, optical absorption, conductivity, and density of gap states from the Fermi level upward toward the conduction band edge of these films have been studied as a function of hydrogen content of the films. The density of states distribution of the films has been deduced from space charge limited current measurements with an Au/a-Si:H Schottky diode structure. Samples with approx.15.5% at. H have densities of states of 3 x 10/sup 14/ states/cm/sup 3/ eV and show large majority carrier mobility-lifetime products of 10/sup -5/ cm/sup 2/V/sup -1/. An Au/a-Si:H diode which is nearly ideal (diode quality factor = 1.05) was obtained for a-Si:H films with hydrogen concentrations of about 16 at. %. The experimental results indicate that a high quality a Si:H material with a low density of states of 3 x 10/sup 14/ states/cm/sup 3/eV can be obtained by r.f. sputtering method.
- Research Organization:
- Iowa State Univ. of Science and Technology, Ames (USA)
- DOE Contract Number:
- W-7405-ENG-82
- OSTI ID:
- 5335936
- Country of Publication:
- United States
- Language:
- English
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