A silicon-based photodiode array was fabricated on a flexible polyethylene terephthalate substrate using a transfer printing technique. A heterojunction structure composed of a 15-nm-thick highly doped hydrogenated amorphous-silicon (n+ a-Si:H) layer and a 3-μm-thick p-type single-crystal silicon (p c-Si) membrane layer was adopted as the active layer of the flexible photodiode. The highly ordered photodiode array formed on the flexible substrate exhibited superior stability in electrical properties under bent conditions with no mechanical deformation. The variation of the spectral quantum efficiency (QE) under short-wavelength light illumination (λ ≤ 580nm) was in excellent agreement with that of a heterojunction photodiode composed of a-Si:H and a bulk c-Si substrate. Relatively low QE values were observed under longer wavelength (λ ≥ 600 nm) illumination due to the finite thickness of the active layer. The C-V measurement results of the fabricated photodiode array were in accordance with the abrupt junction model. A closer inspection of the junction area of the device using high-resolution cross-sectional transmission micrograph exhibited an interface depth of 2 ± 0.5 nm, which is unavoidable in plasma-enhanced a-Si:H deposition processes.
Bibliographical noteFunding Information:
Manuscript received March 5, 2011; revised May 25, 2011 and July 5, 2011; accepted July 7, 2011. Date of publication August 22, 2011; date of current version September 21, 2011. This work was supported in part by the National Research Foundation of Korea under Grant 2010-50193, by the KARI–University Partnership Program, and by the Priority Research Centers Program of National Research Foundation of Korea of the Ministry of Education, Science and Technology under Grant 2009-0093823. The review of this paper was arranged by Editor A. G. Aberle.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Electrical and Electronic Engineering