Influence of plasma deposition on structural and electronic properties of a-Ge:H

Karg, F.; Böhm, H. J.; Pierz, K.

doi:10.1016/0022-3093(89)90622-4

Cited by 71 publications

(9 citation statements)

References 5 publications

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“…On the contrary, the density of a-Ge:H films increases with some particle bombardment during growth. 45 Up to the moment, hydrogenated a-Ge films of improved quality have been prepared either by sputtering 46 or by cathodic 47,48 glow discharge. The data of Fig.…”

Section: Hydrogenation Microstructure and Urbach Edgementioning

confidence: 99%

Exponential absorption edge and disorder in Column IV amorphous semiconductors

Zanatta

Mulato

Chambouleyron

1998

Journal of Applied Physics

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We discuss the likely origin of the exponential absorption tail, or Urbach edge, of fourfold coordinated amorphous ͑a-͒semiconductors. The present analysis is based on a compilation of a considerable amount of experimental data originating from a great variety of samples, alloys, and authors, and obtained with quite different spectroscopic techniques. An attempt is made to correlate the measured Urbach edge with the structural and optical properties of the samples. The present analysis indicates that the Urbach edge may not only reflect the shape of the joint density of states of the valence and conduction band tails, but may also have important contributions from short-range order potential fluctuations produced by charged defects or impurities.

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Section: Hydrogenation Microstructure and Urbach Edgementioning

confidence: 99%

Exponential absorption edge and disorder in Column IV amorphous semiconductors

Zanatta

Mulato

Chambouleyron

1998

Journal of Applied Physics

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“…A low σ d can therefore be considered indicative of good intrinsic a‐Ge:H films. It should be noted that the lowest σ d values reported in Figure 7 are 1‐5 orders of magnitude lower than those reported for all other known a/nc‐Ge:H films, [ 41,42,59–62 ] processed by chemical vapor deposition techniques, to the best of the authors knowledge.…”

Section: Potential Solutions For Processing Ge:hmentioning

confidence: 55%

Opto‐Electrical Properties of Group IV Alloys: The Inherent Challenges of Processing Hydrogenated Germanium

et al. 2022

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In this paper the opto-electrical nature of hydrogenated group IV alloys with optical bandgap energies ranging from 1.0 eV up to 2.3 eV are studied. The fundamental physical principles that determine the relation between the bandgap and the structural characteristics such as material density, elemental composition, void fraction and crystalline phase fraction are revealed. Next, the fundamental physical principles that determine the relation between the bandgap and electrical properties such as the dark conductivity, activation energy, and photoresponse are discussed. The unique wide range of IV valence alloys helps to understand the nature of amorphous (a-) and nanocrystalline (nc-) hydrogenated (:H) germanium films with respect to the intrinsicity, chemical stability, and photoresponse. These insights resulted in the discovery of i) a processing window that results in chemically stable Ge:H films with the lowest reported dark conductivity values down to 4.6•10 -4 (𝛀 •cm) -1 for chemical vapor deposited Ge:H films, and ii) O, C and Sn alloying approaches to improve the photoresponse and chemical stability of the a/nc-Ge:H alloys.

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“…Ϫ1 , re-spectively͒. Karg et al 4 reported Ϸ10 Ϫ6 cm 2 V Ϫ1 for undoped films deposited by a glow discharge method. Marcano et al 13 found Ϸ7ϫ10 Ϫ8 cm 2 V Ϫ1 for rf-sputtered a-Ge:H films of improved quality.…”

Section: Resultsmentioning

confidence: 99%

“…Nevertheless, it was found that to obtain alloy films presenting good optoelectronic properties is rather difficult, the optimum deposition conditions for this purpose being different than those leading to electronic a-Si:H. Studies of deposition conditions and properties of a-Ge:H revealed that films of this material with improved optoelectronic properties can be prepared. [2][3][4][5] As part of this research effort, n-and p-type doping studies of a-Ge:H have been undertaken by our group, using different elements of columns III and V of the Periodic Table as dopant species. [6][7][8][9][10][11][12][13] The measurement of the photoconductivity ͑PC͒ is a valuable tool to investigate the recombination processes and the distribution of deep defect states in the mobility gap of amorphous semiconductors.…”

Section: Introductionmentioning

confidence: 99%

Steady-state photoconductivity of gallium- and indium-doped hydrogenated amorphous germanium thin films

Reis

Comedi

Chambouleyron

1998

Journal of Applied Physics

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The effects of gallium and indium p-type doping on the photoconductivity of hydrogenated amorphous germanium ͑a-Ge:H͒ thin films deposited by the rf-sputtering method are reported. The quantum efficiency-mobility-lifetime ͑͒ product was determined at room temperature as a function of the dark Fermi energy E F on samples with a relative dopant concentration range between Ϸ3ϫ10 Ϫ5 and Ϸ10 Ϫ2. A decrease of is observed with the increase of the Ga concentration until a minimum is reached for compensated samples ͑E F close to midgap level͒, where is about 16 times lower than the value obtained for intrinsic samples. This behavior is followed by an increase as E F crosses the midgap level. Then, for higher Ga doping levels, decreases again. For In-doped samples, on the other hand, a monotonic decrease of is measured for all the impurity concentration range. These results are consistent with a model which assumes that the dangling bond is the main recombination path, and give independent evidence for the lack of correlation between the defect density and E F in p-type doped a-Ge:H.

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Influence of plasma deposition on structural and electronic properties of a-Ge:H

Cited by 71 publications

References 5 publications

Exponential absorption edge and disorder in Column IV amorphous semiconductors

Exponential absorption edge and disorder in Column IV amorphous semiconductors

Opto‐Electrical Properties of Group IV Alloys: The Inherent Challenges of Processing Hydrogenated Germanium

Steady-state photoconductivity of gallium- and indium-doped hydrogenated amorphous germanium thin films

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