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Study on trapping center and trapping effect in MSM ultraviolet photo‐detector on microcrystalline diamond film
Author(s) -
Wang Lanxi,
Chen Xuekang,
Wu Gan,
Guo Wantu,
Wang Yunfei,
Cao Shengzhu,
Shang Kaiwen,
Han Weihua
Publication year - 2010
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.200925042
Subject(s) - responsivity , optoelectronics , photoconductivity , materials science , diamond , trapping , carrier lifetime , photoelectric effect , charge carrier , chemical vapor deposition , semiconductor , optics , silicon , photodetector , physics , ecology , composite material , biology
A MSM (metal‐semiconductor‐metal) ultraviolet (UV) photo‐detector was fabricated on a high‐quality diamond film deposited by microwave chemical vapor deposition on a Si substrate. Charge‐based deep level transient spectroscopy (Q‐DLTS) was used for obtaining the information on activation energy ( E a ), capture cross section ( σ s ) and concentration ( N t ) of trapping centers in the band gap of the diamond film. A shallow level with E a = 0.213 eV, σ s = 9.88 × 10 −20 cm 2 and N t = 1.1 × 10 11 cm −2 is present in the diamond film. The shallow level may not act as effective recombination center due to the so small activation energy according to the Schockly‐Read‐Hall statistics. The UV photo‐detector presents slow time response, high responsivity and high photoconductive gain under irradiation of 220 nm monochromatic light. These performances indicate that minority carrier trapping effect may play an important role in the UV photo‐detector. The photo‐generated minority carriers (electrons in this work) may be trapped by the shallow level during light irradiation process and then de‐trap slowly via thermal excitation or tunnelling effect after removing the light source, which contributes to the prolonged response time. The trapping effect can also reduce the carrier recombination probability, resulting in the high responsivity and high photoconductive gain.