Photoconductivity spectroscopy (CPM) on a-Ge:H at low temperatures

Scholz, Andreas; Müller, B.; Schröder, Bernd; Freistedt, H.

doi:10.1016/0022-3093(93)90568-i

Cited by 7 publications

(3 citation statements)

References 10 publications

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“…In this study deep defect density of states were obtained by three different capacitance techniques. Although the techniques for the determination of density of states were different, qualitative agreement with those reported previously by other authors [5,19], 5 × 10 17 cm −3 , 9 × 10 17 cm −3 have been obtained.…”

Section: The Capacitance-frequency Methodssupporting

confidence: 90%

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Determination of the distribution of electronic states in hydrogenated amorphous germanium by capacitance techniques

Seri̇n¹,

Serin²,

Schröder³

2003

Semicond. Sci. Technol.

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In this study we have determined the density of states below the Fermi level in hydrogenated amorphous germanium thin films by different capacitance techniques. In order to realize the goal, a-Ge:H films were first deposited on c-Ge substrates and later they were converted into Cu/c-Ge/a-Ge:H/Al sandwich structures. The current-voltage and capacitance-voltage-frequency characteristics of the samples were measured at various temperatures. The forward current initially increased exponentially with an increase in the applied voltage up to 0.25 V and then continued to increase nonexponentially. It was found that the carrier transport mechanism in the exponential region is limited by tunnelling and the activation energy of the junction was obtained from this region to be 0.57 eV. The gap states below the Fermi level were determined by three different methods: differential capacitance-voltage method, drive-level capacitance method and capacitance-energy method. Defect densities of the order of 2 × 10 17 eV −1 cm −3 at just below the Fermi level have been obtained for our a-Ge:H samples.

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Section: The Capacitance-frequency Methodssupporting

confidence: 90%

“…However, much less work has been done on the opto-electronic properties of a-Ge:H since a-Ge:H films exhibit a larger density of states than a-Si:H films [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Determination of the distribution of electronic states in hydrogenated amorphous germanium by capacitance techniques

Seri̇n¹,

Serin²,

Schröder³

2003

Semicond. Sci. Technol.

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“…Illuminating the sample again for 150 h led to a decrease of about 6% in I p (t) after all. These results suggest that few LIMDs are generated in narrow-bandgap a-Ge : H, compared with a-Si : H. The CPM may be useful for studying midgap optical absorption (optical absorption related to midgap defect states), but the poor photosensitivity of a-Ge : H sometimes prevents LEOA measurements by CPM at room temperature (Scholz et al 1993). Our high-quality sample, however, enables us to measure optical absorption coe cients a < 0´1 cm -1 below ht = 0´5 eV, using CPM even at room temperature.…”

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confidence: 91%