Having used thermally stimulated conductivity (TSC) technique, we identified deep electron traps that produce strong effects on charge carrier transport and photoconductivity in InGaAs/GaAs quantum dot (QD) structures. The values of deep levels below the conduction band of GaAs at 0.16, 0.22, and 0.35 eV are obtained from the analysis of the shapes of TSC curves after the excitation with the quanta energy hv = 0.9, 1.2, and 1.6 eV. The level 0.16 eV in depth is an effective electron trap that provides crossing of lateral conductivity with a high-resistance mode and, therefore, causes a high photocurrent sensitivity of about 3 A/W at 77 K with excitation by interband transitions in QDs. We determined the charge density of electrons captured by the (Ec – 0.16 eV) level to be 2 × 10−6 C/cm2 at 77 K that induces electric field ∼ 105 V/cm in a vicinity of QDs. The state at Ec – 0.22 eV is shown to be related to the recombination center that can hold non-equilibrium holes over a long time under the condition that the non-equilibrium holes are localized by the quantum states of QDs. In the course of long-term electron storage in a vicinity of QDs, an electron trapped at the (Ec – 0.16) eV level can be recaptured by a deeper spatially remote (Ec – 0.22 eV) level that allows the TSC peak observation at 106 K.

Suppression of the photoluminescence quenching effect in self-assembled In As ∕ Ga As quantum dots Appl. Phys. Lett. 87, 053109 (2005) The in-plane photoconductivity and photoluminescence are investigated in quantum dot-chain InGaAs/GaAs heterostructures. Different photoconductivity transients resulting from spectrally selecting photoexcitation of InGaAs QDs, GaAs spacers, or EL2 centers were observed. Persistent photoconductivity was observed at 80 K after excitation of electron-hole pairs due to interband transitions in both the InGaAs QDs and the GaAs matrix. Giant optically induced quenching of in-plane conductivity driven by recharging of EL2 centers is observed in the spectral range from 0.83 eV to 1.0 eV. Conductivity loss under photoexcitation is discussed in terms of carrier localization by analogy with carrier distribution in disordered media. V C 2014 AIP Publishing LLC.

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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.

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