Low-dark-current heterojunction phototransistors with long-term stable passivation induced by neutralized (NH4)2S treatment

Shao Yen Chiu, Hon Rung Chen, Wei Tien Chen, Meng Kai Hsu, Wen Chau Liu, Jung Hui Tsai, Wen Shiung Lour

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

To investigate the effects of surface leakage on the temperature-dependent dark and optical performance of a heterojunction phototransistor (HPT), three sets of HPTs were prepared. They were unpassivated (HPT A), passivated with diluted (NH4)2S (HPT B), and passivated with neutralized (NH4)2S (HPT C). Passivation treatment successfully suppresses surface-defect-induced effects. The passivated HPTs exhibit a reduced dark current and an enhanced signal-to-noise ratio (SNR). HPT A exhibits a room-temperature collector dark current (ICdark) of 0.59 nA at a VCE of 1V, while those of HPTs B and C are 0.03 and 0.89pA, respectively. The room-temperature SNR values for HPTs A, B, and C at a P in of 8.3 (107.6) nW are 5.9 (42), 59 (91), and 91 (122) dB, respectively. After a three-week air exposure, the room-temperature SNR at a Pin of 107.6 nW decreases to 25 (67) dB for HPT A (B), while it is 116 dB for HPT C. The decrease for HPT C is only 6 dB. A long-term stable passivation with good thermal stability has been achieved by neutralized (NH4)2S treatment.

Original languageEnglish
Pages (from-to)35-42
Number of pages8
JournalJapanese journal of applied physics
Volume47
Issue number1
DOIs
Publication statusPublished - 2008 Jan 18

All Science Journal Classification (ASJC) codes

  • General Engineering
  • General Physics and Astronomy

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