Photocurrent multiplication in Ga2O3/CuInGaSe2 heterojunction photosensors

Kenji Kikuchi, Shigeyuki Imura, Kazunori Miyakawa, Hiroshi Ohtake, Misao Kubota, Eiji Ohta

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Photocurrent multiplication was observed in gallium oxide (Ga2O3)/Cu(In,Ga)Se2 (CIGS) heterojunction photosensors. In this study, we investigated the electrical and optical properties of Ga2O3/CIGS heterojunction photodiodes for possible use as high-sensitivity visible-light sensors. To achieve low current density J under dark conditions, a thin layer of Ga2O3, which is an n-type wide band gap (4.7-4.9 eV) semiconductor, was grown on the CIGS layer. This Ga2O3 layer functioned as a hole-blocking layer and buffer layer. The effect of oxygen partial pressure during the deposition of the Ga2O3 layer was also examined. With no applied voltage, the quantum efficiency of a photodiode with a Ga2O3 layer deposited with no oxygen partial pressure was considerably high. On the other hand, when the Ga2O3 layer was deposited with oxygen partial pressure, the depletion region almost spread into the Ga2O3 layer with no applied voltage. Considering J, under low oxygen deposition conditions, dark current J increased due to more oxygen vacancies, and with higher oxygen partial pressure during deposition, dark current J increased due to oxygen plasma damage at the Ga2O3/CIGS interface during the sputtering deposition. The photodiode with the lowest dark current J of 10-9 A/cm2 at applied voltages less than 3 V had a Ga2O3 layer deposited at an optimum oxygen partial pressure of 6.0 × 10-2 Pa. The average quantum efficiency for this photodiode in the visible light range (400-700 nm) was 85% at an applied voltage of 3 V. Moreover, at higher applied voltages, carrier multiplication phenomena were observed, and the average quantum efficiency (400-700 nm) was over 100% at applied voltages over 4 V.

Original languageEnglish
Pages (from-to)24-29
Number of pages6
JournalSensors and Actuators, A: Physical
Volume224
DOIs
Publication statusPublished - 2015 Apr 1

Fingerprint

photosensors
Photocurrents
multiplication
photocurrents
Heterojunctions
heterojunctions
Oxygen
Partial pressure
Photodiodes
Dark currents
Electric potential
partial pressure
Quantum efficiency
oxygen
photodiodes
dark current
electric potential
quantum efficiency
Gallium
Oxygen vacancies

Keywords

  • Avalanche multiplication
  • CIGS
  • Dark current
  • Dark current
  • Image sensor

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Condensed Matter Physics
  • Electronic, Optical and Magnetic Materials
  • Metals and Alloys
  • Surfaces, Coatings and Films
  • Instrumentation

Cite this

Photocurrent multiplication in Ga2O3/CuInGaSe2 heterojunction photosensors. / Kikuchi, Kenji; Imura, Shigeyuki; Miyakawa, Kazunori; Ohtake, Hiroshi; Kubota, Misao; Ohta, Eiji.

In: Sensors and Actuators, A: Physical, Vol. 224, 01.04.2015, p. 24-29.

Research output: Contribution to journalArticle

Kikuchi, Kenji ; Imura, Shigeyuki ; Miyakawa, Kazunori ; Ohtake, Hiroshi ; Kubota, Misao ; Ohta, Eiji. / Photocurrent multiplication in Ga2O3/CuInGaSe2 heterojunction photosensors. In: Sensors and Actuators, A: Physical. 2015 ; Vol. 224. pp. 24-29.
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