Low Dark Current Operation in InAs/GaAs(111)A Infrared Photodetectors: Role of Misfit Dislocations at the Interface

Abstract

We demonstrate an extended short-wave infrared (e-SWIR) photodetector composed of an InAs/GaAs(111)A heterostructure with interface misfit dislocations. The layer structure of the photodetector consists simply of an n-InAs optical absorption layer directly grown with a thin undoped-GaAs spacer layer on n-GaAs by molecular beam epitaxy. The lattice mismatch was abruptly relaxed by forming a misfit dislocation network at the initial stage of the InAs growth. We found high-density threading dislocations (1.5 × 10 9 cm −2 ) in the InAs layer. The current−voltage characteristics of the photodetector at 77 K had a very low dark current density (<1 × 10 −9 A cm −2 ) at a positive applied voltage (electrons flow from n-GaAs to n-InAs) of up to ∼+1 V. Simulation of the band structure revealed that the direct connection of GaAs and InAs and the formation of interfacial states by the misfit dislocations play significant positive roles in suppressing dark current. Under illumination with e-SWIR light at 77 K, a clear photocurrent signal was observed with a 2.6 μm cutoff wavelength, which is consistent with the bandgap of InAs. We also demonstrated e-SWIR detection at room temperature with a 3.2 μm cutoff wavelength. The maximum detectivity at 294 K exceeds 2 × 10 8 cm Hz 0.5 W −1 for the detection of e-SWIR light at 2 μm.

Initial stage of InSb heteroepitaxial growth on GaAs (111)A: effect of thin InAs interlayers

“…21) Earlier studies have shown that in the lattice-mismatched system of InAs on GaAs(111)A, the formation of three-dimensional islands is effectively inhibited by introducing misfit-dislocation network at the interface. [22][23][24][25] The layer-by-layer growth continues throughout the growth, which is in stark contrast to that for the (100) orientation where Stranki-Krastanow growth occurs. [26][27][28] The layer-by-layer growth was also realized for InSb on GaAs(111)A by combining the two-step growth technique, and the 200 nm thick InSb layer exhibits mobility close to ∼10 000 cm 2 V −1 s −1 .…”

Conduction characteristics of n-InAs/n-GaAs heterojunctions with misfit dislocations

“…[9][10][11][12] Very recently, an n-InAs/n-GaAs heterojunction photodetector was proposed, where misfit dislocations are generated at the interface and form a network-like structure. 25) The photodetector exhibits a low dark current up to a high applied voltage V a : the dark current is about 2.7 × 10 −2 A cm −2 at V a = 1.0 V and T = 250 K. The aim of this work is to clarify the origin of the suppression of the dark current and the roles of the interface states due to the misfit dislocations. We carry out the measurement of current-voltage (I-V ) characteristics in the n-InAs/n-GaAs heterojunction and analyze the I-V data in detail.…”

Strain-Engineering-Driven Photomechanical–Photoelectric Coupled Flexible Photodetector Based on Hexagonal Silicon Nanowire Films

“…Detectors for broadband optical signals consist of two main classes. One is narrow band gap semiconductors (such as germanium, , group III–V/II–VI compounds, , other narrow band gap two-dimensional materials, and colloidal quantum dots with tunable band gaps , ) and the other is all-silicon detectors which utilize two-photon absorption, , sub-band gap absorption, , surface-state absorption, , and optically assisted carrier tunneling absorption physical effects of silicon to achieve light absorption below the energy gap. Considering requirements such as room-temperature operation, nontoxicity, and low cost, all-silicon detectors offer unparalleled advantages over these narrow band gap semiconductor detectors.…”