Photoconductivity peculiarities in InGaAs quantum wire heterostructures: anisotropy and high photoresponsivity at room temperature

Abstract

The anisotropy of photoconductivity was measured in InGaAs/GaAs quantum wire heterostructures. This anisotropy is the result of a one-dimensional band creating an effective channel for photo-generated carriers. High photoresponsivity of ∼ 2.3 A W −1 at 0.3 μW cm −2 incident light excitation was revealed at the InGaAs band edge absorption at room temperature. We show that the observation of this high photoresponsivity at lower power densities is due to the presence of both local electric fields at the InGaAs/GaAs interface caused by structural non-uniformities and a trap at ∼ 68 meV below the GaAs conductivity band edge. A proposed lateral one-dimensional photoconductive heterosystem is a good candidate for high sensitivity, low-bias infrared detectors.

Thermally stimulated conductivity in InGaAs/GaAs quantum wire heterostructures

“…It means that in addition to recombination centers, long term electronic traps (shallow trap centers) have a significant impact on PC decay [4,6]. shows the extended relaxation (residual photoconductivity), when conductivity is not returned to its equilibrium value for a long (~30 s) time, under excitation hν 1 = 1.35 eV at temperatures between 120 and 150 K. We can distinguish two peaks of thermal conductivity in the dark background of conductivity (dashed curve), which is measured under similar experimental conditions, but without photoexcitation.…”

“…3). Besides electron transitions between ground states of conduction and valence bands of InGaAs QWR (arrow 1), the PC signal below band gap of GaAs is the result of photoexcited electrons in both the buffer layer (arrow 2) and defect states of GaAs (arrows 4 and 5) [4]. Band-to-band absorption in GaAs is observed above 1.43 eV (arrow 3).…”

“…Nowadays the interest in studying the physical properties of heterostructures InGaAs-GaAs, specifically centers with deep and shallow trap levels, has increased significantly [4][5][6][7]. It is caused by its successful use to solve the scientific and technical problems for several years.…”

Deep level centers and their role in photoconductivity transients of InGaAs/GaAs quantum dot chains

“…The InGaAs/GaAs interfaces and InGaAs nanostructures are responsible for the observed transport peculiarities which are mainly caused by inhomogeneities of local electro-physical properties. 44,45 First of all, the intermediate region of the InGaAs/GaAs interface contains the defects: EL2, EL6, etc., which have a wide spectrum of deep levels in the GaAs bandgap. 15,18 Spatial distribution of captured electrons and ionized defects as well as strain fields, local variations of the InGaAs alloy composition, size fluctuations, or interface roughness could result in local electrostatic variations of the crystal potential in the GaAs close to the QD or QWR region.…”

Photoconductivity Relaxation Mechanisms of InGaAs/GaAs Quantum Dot Chain Structures

“…Moreover, observation of the effective radiative recombination involving InGaAs quantum-sized states and PC nonlinearities [21] gives further evidence of strong impact of InGaAs on PC relaxation. This was taken into account for formula (5), which has received confirmation during PC kinetics analysis of the samples, excited by radiation with λ = 980 nm, when bimolecular recombination can dominate.…”