Electrical and optical properties of Ga2O3/CuGaSe2 heterojunction photoconductors

Kikuchi, Kenji; Imura, Shigeyuki; Miyakawa, Kazunori; Kubota, Minoru; Ohta, Eiji

doi:10.1016/j.tsf.2013.10.036

Cited by 14 publications

(9 citation statements)

References 16 publications

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“…Signal current was almost zero at no applied voltage. The depletion region extended mostly in the Ga 2 O 3 layer because its carrier density was significantly lower than that of the CIGS layer as described later [4,40,41]. The signal current drastically increased when a voltage of more than 2 V was applied, indicating that the depletion region was spreading into the CIGS layer.…”

Section: Resultsmentioning

confidence: 85%

“…As pixel sizes of image sensors decrease and frame rates increase, the incident light intensity on one pixel per scan decreases; hence, highersensitivity image sensors are required. We have been developing films with low-voltage signal-current multiplication to increase the sensitivity of visible-light image sensors using avalanche multiplication phenomena [4]. Avalanche multiplication usually requires a high electric field of ∼10 6 V/m, which is a problem because the withstand voltage of an imaging device readout circuit is generally less than several dozen volts [5,6].…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, the photoconversion layer's thickness has to be less than a few microns to generate a high electric field within the withstand voltage of the readout circuit. We have been investigating Cu(In,Ga)Se 2 (CIGS) thin films for the photoconversion layer [4]. CIGS thin films have been developed for high-efficiency solar cells [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

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Photocurrent multiplication in Ga2O3/CuInGaSe2 heterojunction photosensors

Kikuchi¹,

Imura²,

Miyakawa³

et al. 2015

Sensors and Actuators A: Physical

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Section: Resultsmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Photocurrent multiplication in Ga2O3/CuInGaSe2 heterojunction photosensors

Kikuchi¹,

Imura²,

Miyakawa³

et al. 2015

Sensors and Actuators A: Physical

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“…For a better understanding, a comparative schematic energy band diagram of S0 and S1–S4 are shown in Figure b, respectively. The bandgap ( E g ) and electron affinity (χ) are taken as 5 and 4 eV for Ga 2 O 3 , respectively, and the work function of ITO is 4.9 eV . The Fermi level (zero binding energy in the XPS spectra) of undoped Ga 2 O 3 is approximately in the middle of the gap.…”

Section: Resultsmentioning

confidence: 99%

Room‐Temperature Fabricated Amorphous Ga₂O₃ High‐Response‐Speed Solar‐Blind Photodetector on Rigid and Flexible Substrates

Cui

Mei

Zhang

et al. 2017

Advanced Optical Materials

264

203

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A solution to the fabrication of amorphous Ga2O3 solar‐blind photodetectors on rigid and flexible substrates at room temperature is reported. A robust improvement in the response speed is achieved by delicately controlling the oxygen flux in the reactive radio frequency magnetron sputtering process. Temporal response measurements show that the detector on quartz has a fast decay time of 19.1 µs and a responsivity of 0.19 A W−1 as well, which are even better than those single crystal Ga2O3 counterparts prepared at high temperatures. X‐ray photoelectron spectroscopy and current–voltage tests suggest that the reduced oxygen vacancy concentration and the increased Schottky barrier height jointly contribute to the faster response speed. Amorphous Ga2O3 solar‐blind photodetector is further constructed on polyethylene naphthalate substrate. The flexible devices demonstrate similar photoresponse behavior as the rigid ones, and no significant degradation of the device performance is observed in bending states and fatigue tests. The results reveal the importance of finely tuned oxygen processing gas in promoting the device performance and the applicability of room‐temperature synthesized amorphous Ga2O3 in fabrication of flexible solar‐blind photodetectors.

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“…[13] A fast and dry-deposited Ga 2 O 3 buffer layer by sputtering and a Cu(In,Ga)Se 2 (CIGS) as thin-film solar cell absorber material would be an ideal combination. In the past, Ga 2 O 3 was applied to chalcopyritetype materials, such as Ga 2 O 3 /CuGaSe 2 heterojunction photoconductors, [18] a-Ga 2 O 3 /CIGS heterojunction photosensors, [19] or a-Ga 2 O 3 applied on the CIGS surface in CIGS thin-film solar cells. [13,14,20] In this work, we deposit a-Ga 2 O 3 by RF magnetron sputtering from a ceramic target and examine its suitability as buffer layer in thin-film solar cells based on industry-relevant inline CIGS absorbers grown by thermal coevaporation.…”

Section: Introductionmentioning

confidence: 99%

The Application of Sputtered Gallium Oxide as Buffer for Cu(In,Ga)Se₂ Solar Cells

Witte

Paetel

Menner

et al. 2021

Physica Rapid Research Ltrs

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Crystalline gallium oxide is a promising wide‐bandgap semiconductor material, especially for applications in high‐frequency and high‐power devices. With an optical bandgap energy well above 4 eV, which implies no visible light absorption, it is also a candidate for one of the front‐side layers in thin‐film solar cells. X‐ray amorphous gallium oxide (a‐Ga2O3) deposited by RF magnetron sputtering is applied as an n‐type buffer layer in substrate‐type configuration solar cells based on industry‐relevant inline coevaporated Cu(In,Ga)Se2 (CIGS) absorbers, which include an i‐ZnO/ZnO:Al bilayer as the front electrode. The cells exhibit an efficiency peak at Ga2O3 deposition temperatures in the range of 140–180 °C and show mostly a gain in short‐circuit current density compared with the CdS‐buffered reference cells, as a result of the high optical bandgap of a‐Ga2O3 in the range of 4.6–4.8 eV. The CIGS solar cells with sputtered a‐Ga2O3 buffers reach efficiencies of almost 14%, lacking in open‐circuit voltage and fill factor, whereas the CdS‐buffered cells are on a 16–17% level. Light soaking of the cells leads to a slight improvement of the fill factor, but the gap in open‐circuit voltage of 80–100 mV in contrast to the CdS‐buffered reference cells remains unaffected.

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Electrical and optical properties of Ga2O3/CuGaSe2 heterojunction photoconductors

Cited by 14 publications

References 16 publications

Photocurrent multiplication in Ga2O3/CuInGaSe2 heterojunction photosensors

Photocurrent multiplication in Ga2O3/CuInGaSe2 heterojunction photosensors

Room‐Temperature Fabricated Amorphous Ga₂O₃ High‐Response‐Speed Solar‐Blind Photodetector on Rigid and Flexible Substrates

The Application of Sputtered Gallium Oxide as Buffer for Cu(In,Ga)Se₂ Solar Cells

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Electrical and optical properties of Ga2O3/CuGaSe2 heterojunction photoconductors

Cited by 14 publications

References 16 publications

Photocurrent multiplication in Ga2O3/CuInGaSe2 heterojunction photosensors

Photocurrent multiplication in Ga2O3/CuInGaSe2 heterojunction photosensors

Room‐Temperature Fabricated Amorphous Ga2O3 High‐Response‐Speed Solar‐Blind Photodetector on Rigid and Flexible Substrates

The Application of Sputtered Gallium Oxide as Buffer for Cu(In,Ga)Se2 Solar Cells

Contact Info

Product

Resources

About

Room‐Temperature Fabricated Amorphous Ga₂O₃ High‐Response‐Speed Solar‐Blind Photodetector on Rigid and Flexible Substrates

The Application of Sputtered Gallium Oxide as Buffer for Cu(In,Ga)Se₂ Solar Cells