Photoelectric properties of the metamorphic InAs/InGaAs quantum dot structure at room temperature

Abstract

Articles you may be interested inCalculation of metamorphic two-dimensional quantum energy system: Application to wetting layer states in InAs/InGaAs metamorphic quantum dot nanostructures Single quantum dot emission at telecom wavelengths from metamorphic InAs/InGaAs nanostructures grown on GaAs substrates Appl. Phys. Lett. 98, 173112 (2011); 10.1063/1.3584132 Properties of wetting layer states in low density InAs quantum dot nanostructures emitting at 1.3 μ m : Effects of InGaAs cappingWe present the study of optical and photoelectric properties of InAs quantum dots (QDs) grown on a metamorphic In 0.15 Ga 0.85 As buffer layer: such nanostructures show efficient light emission in the telecom window at 1.3 lm (0.95 eV) at room temperature. We prepared a sample with vertical geometry of contacts isolated from the GaAs substrate. The structure is found to be photosensitive in the spectral range above 0.9 eV at room temperature, showing distinctive features in the photovoltage and photocurrent spectra attributed to QDs, InAs wetting layer, and In 0.15 Ga 0.85 As metamorphic buffer, while a drop in the photoelectric signal above 1.36 eV is related to the GaAs layer. No effect of defect centers on the photoelectrical properties is found, although they are observed in the absorption spectrum. We conclude that metamorphic QDs have a low amount of interface-related defects close to the optically active region and charge carriers can be effectively collected into InAs QDs. V C 2015 AIP Publishing LLC. [http://dx.

Comparative Study of Photoelectric Properties of Metamorphic InAs/InGaAs and InAs/GaAs Quantum Dot Structures

“…The features of the metamorphic InAs/In 0.15 Ga 0.85 As QD structure spectrum in Fig. 3(a) have been identified elsewhere [30]. In particular, the threshold at 0.68 eV is related to the EL2 family defect centers [22–29].…”

“…As discussed in Ref. [30], undoped layers were used to separate QDs from n -doped regions to reduce the effect of non-radiative recombination centers, thus maximizing the QD light emission efficiency.

Fig. 1( Color online ) Schematics of the metamorphic InAs/In 0.15 Ga 0.85 As/ si -GaAs and InAs/GaAs/ si -GaAs QD samples investigated: layer thickness, composition, and doping are indicated; AFM images of the uncapped structures are shown as well

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Bipolar Effects in Photovoltage of Metamorphic InAs/InGaAs/GaAs Quantum Dot Heterostructures: Characterization and Design Solutions for Light-Sensitive Devices

“…Vertical photocurrent and PV spectra were measured in the 0.6 to 1.8 eV range using normal incidence excitation geometry at room temperature (RT) (300 K) and same light source intensity (1.5 mW/cm 2 ). The photocurrent was measured using a current amplifier and direct current technique [ 10 , 43 – 45 ], with 1 V bias. The current was measured as a voltage signal drop across a series load resistance of 100 kΩ (see the inset in Fig.…”

“…Although significant efforts are devoted to avoid the substrate influence, the photoresponse is affected by both the substrate and nearby layers grown by molecular beam epitaxy (MBE). Thus, while the applied contact geometry is to retain the bottom layers and substrate electrically inactive, a notable negative effect of them on PV and photocurrent has been detected by us in a previous investigation [ 43 ]. Very recently, we compared the photoelectric properties of the metamorphic InAs/In 0.15 Ga 0.85 As QD structure with those of a standard InAs/GaAs QD one and found that the photocurrent of metamorphic InAs/In 0.15 Ga 0.85 As heterostructures was not affected by levels related to defects in the vicinity of QD [ 45 ].…”

“…Photovoltage (PV) or photoconductivity (PC) studies is an ideal tool for the determination of the photoresponse as function of light energy, transitions between levels, carrier transport, and operating range of the device [ 10 , 43 , 44 ]. However, despite that some studies of the photoelectric properties of structures with metamorphic InAs QDs have been performed in last years [ 37 – 39 , 43 ], full aspects of the photoresponse mechanism still remain unclear, as along with the influence of the MB on the properties of the nanostructures. In particular, effects of the GaAs substrate and related interfaces on the photoelectric spectra of InAs/InGaAs/GaAs QD structures have not been explored in details.…”