Variations of work function and surface conductivity on clean cleaved zinc oxide surfaces by annealing and by hydrogen adsorption

Moormann, H.; Köhl, D.; Heiland, G.

doi:10.1016/0039-6028(80)90374-x

Cited by 82 publications

(65 citation statements)

References 16 publications

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“…Under these conditions and after 15 min Ar-sputtering, the work function of CuGaSe 2 is 4.96 eV. For the highly n-doped ZnO we determine a work function of 4.26 eV, in reasonable agreement with results from Moormann et al [36]. Up to a sputtering time of 30 min only the work function of the p-type semiconductors changes significantly.…”

Section: Cross-sectional Studies On Complete Devicessupporting

confidence: 79%

Electronic Properties of Surfaces and Interfaces in Widegap Chalcopyrites

Sadewasser

2006

Wide-Gap Chalcopyrites

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Chalcopyrite solar cells consist of a layered stack of several metallic and semiconducting materials. As light-induced charge carriers are transported perpendicular to the layers, the interfaces between the layers are of paramount importance for device efficiency. This chapter describes the application of Kelvin probe force microscopy to research on chalcopyrite materials and solar cell devices. The technique is used to measure the sample's work function with a lateral resolution in the nm range. After introducing the experimental technique, we review results on surface inhomogeneities on the local scale, including orientation-dependent work function, foreign phases and grain boundaries. In a separate section measurements on complete solar cell devices in a cross-sectional arrangement are introduced and discussed.

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Section: Cross-sectional Studies On Complete Devicessupporting

confidence: 79%

Electronic Properties of Surfaces and Interfaces in Widegap Chalcopyrites

Sadewasser

2006

Wide-Gap Chalcopyrites

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“…Using an electron affinity of ϭ4.1 eV and a band gap of 1.67 eV, the position of the Fermi energy results to 0.8 eV above the valence band maximum, in agreement with slightly Ga rich CGSe samples. 10 For the highly n-doped ZnO we determine a work function of 4.26 eV, in reasonable agreement with results from Moormann et al 11 In Fig. 3 it can also be seen, that up to a sputtering time of 30 min only the p-type semiconductors change the work function significantly.…”

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confidence: 79%

CuGaSe 2 solar cell cross section studied by Kelvin probe force microscopy in ultrahigh vacuum

Glatzel

Marrón

Schedel‐Niedrig

et al. 2002

Applied Physics Letters

106

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Kelvin probe force microscopy under ultrahigh vacuum conditions has been used to image the electronic structure of a Mo/CuGaSe2/CdS/ZnO thin film solar cell. Due to the high energy sensitivity together with a lateral resolution in the nanometer range we obtained detailed information about the various interfaces within the heterostructure. The absolute work function of the different materials was measured on a polished cross section. To obtain a flat and clean surface we optimized the sputtering process with Ar ions. The presence of an additional MoSe2 layer between the Mo backcontact and the CuGaSe2 absorber layer was observed.

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“…1-5͔͒ shows that stable and rectifying metal contacts to ZnO remain a challenge. Indeed, surface traps, adsorbates, 3,4 processing, 1,5 hydrogen, 6 orientation, and surface dipoles 7 can all affect ZnO's surface and interface properties. Here we use nanoscale depth-resolved cathodoluminescence spectroscopy ͑DRCLS͒ coupled with surface science and electronic transport techniques to separate these extrinsic effects and show that near-interface native defects, both resident in the bulk and created by metallization, dominate rectification, recombination, and tunneling features of the metal-ZnO contact.…”

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confidence: 99%

Dominant effect of near-interface native point defects on ZnO Schottky barriers

Brillson

Mosbacker

Hetzer

et al. 2007

Applied Physics Letters

153

105

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The authors used depth-resolved cathodoluminescence spectroscopy and current-voltage measurements to probe metal-ZnO diodes as a function of native defect concentration, oxygen plasma processing, and metallization. The results show that resident native defects in ZnO single crystals and native defects created by the metallization process dominate metal-ZnO Schottky barrier heights and ideality factors. Results for ZnO(0001¯) faces processed with room temperature remote oxygen plasmas to remove surface adsorbates and reduce subsurface native defects demonstrate the pivotal importance of crystal growth quality and metal-ZnO reactivity in forming near-interface states that control Schottky barrier properties.

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Variations of work function and surface conductivity on clean cleaved zinc oxide surfaces by annealing and by hydrogen adsorption

Cited by 82 publications

References 16 publications

Electronic Properties of Surfaces and Interfaces in Widegap Chalcopyrites

Electronic Properties of Surfaces and Interfaces in Widegap Chalcopyrites

CuGaSe 2 solar cell cross section studied by Kelvin probe force microscopy in ultrahigh vacuum

Dominant effect of near-interface native point defects on ZnO Schottky barriers

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