Journal
ACS APPLIED MATERIALS & INTERFACES
Volume 11, Issue 22, Pages 20157-20166Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acsami.9b04248
Keywords
CIGS heterojunctions; thin-film photodetectors; atomic-layer deposition; Al2O3 interfacial layer; self-powered; high detectivity
Funding
- National Natural Science Foundation of China [61604061, 51772135]
- Ministry of Education of China [6141A02022516]
- Natural Science Foundation of Guangdong Province, China [2014A030306010]
- Guangzhou Municipal Science and Technology Bureau [201804020031]
- Fundamental Research Funds for the Central Universities [21618405]
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The Cu(In,Ga)Se-2 (GIGS) thin film has been commercialized as solar cells with great success, but its application for photodetectors still faces some practical challenges, including low detectivity and long response time. In this paper, the structure of the Mo/CIGS/CdS/ZnO/ITO heterojunction has been fabricated, and satisfactory performances of high detectivity and fast response time have been achieved by suppressing the dark current and enhancing the carrier mobility. The controllable growth of CIGS grains is accomplished through optimizing the selenization process, demonstrating that bigger grain sizes resulted in higher carrier mobility and better response characteristics. Particularly, the high rise/decay speed of 3.40/6.46 mu s is achieved. Furthermore, the interface of the CIGS/CdS heterojunction has been modified by the Al2O3 layer via the atomic-layer deposition (ALD) process. The dark current of the device is effectively suppressed by the ALD-Al2O3 layer, which remarkably drops from similar to 10(-7) to similar to 10(-9) A. As a consequence, the detectivity rises from 3.08 X 10(11) to 1.84 X 10(12) Jones. In addition, the ALD-Al2O3 layer shows a protective effect as well, which is positive for photoelectrical conversion. Besides, the wide linear dynamic range of 102.1 dB and large -3 dB bandwidth of 78 kHz are acquired. This work suggests that the CIGS-based heterojunction has great potential for high-performance thin-film photodetectors.
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