Effect of rapid thermal annealing on the noise properties of InAs∕GaAs quantum dot structures

Abstract

Combined optical and electrical studies of the effects of annealing on the intrinsic states and deep levels in a self-assembled InAs quantum-dot structure Self-assembled InAs quantum dots ͑QDs͒ were grown by molecular beam epitaxy ͑MBE͒ on n + -GaAs substrates, capped between 0.4 m thick n-type GaAs layers with electron concentration of 1 ϫ 10 16 cm −3 . The effect of rapid thermal annealing at 700°C for 60 s on the noise properties of the structure has been investigated using Au/ n-GaAs Schottky diodes as test devices. In the reference sample without containing QDs, the noise spectra show a generation-recombination ͑g-r͒ noise behavior due to a discrete energy level located about 0.51 eV below the conduction band edge. This trap is ascribed to the M4 ͑or EL3͒ trap in GaAs MBE layers, related to a chemical impurity-native defect complex. In the structure with embedded QDs, the observed g-r noise spectra are due to a midgap trap level ascribed to the EL2 trap in GaAs, which is related to the InAs QDs dissolution due to the thermal treatment.

Low-frequency noise properties in Pt-indium gallium zinc oxide Schottky diodes

“…8,9 Analysis of LFN can also be used to improve the device performance and provide substantial information on physical properties. So far, the LFN properties of Schottky diodes have only been studied on crystalline semiconductors like gallium arsenide, [10][11][12] silicon (Si), [13][14][15][16] silicon carbide, 17 zinc oxide 18 and conventional amorphous semiconductors like a-Si. 19 The results often exhibit 1/f noise power spectral density which is proportional to I n , where n varies from 1 to 2.…”

Rapid thermal annealing temperature dependence of noise properties in Au/n‐GaAs Schottky diodes with embedded InAs quantum dots in asymmetric In0.2Ga0.8As wells

“…In GaAs this trap is called EL2 defect and is related to an As antisite defect or to a GaAs native defect associated with the antisite. Such defects can be created by the inter-diffusion process due to the RTA treatment [12].…”

“…For higher annealing temperatures, the QDs dissolute and a single quantum well is formed [8][9][10]. The g-r noise component indicates the existence of a distinct trap level in the bulk of the GaAs capping layer [12]. The spectrum of g-r noise, arising from trapping detrapping processes between conduction band states and a monoenergetic trap level, can be written as [15]:…”

“…Recent investigations of the electrical properties of Au/n-GaAs Schottky diodes with InAs QDs by means of low frequency noise measurements demonstrated that, after rapid thermal annealing at 700 °C, the QDs dissolution is related with a trap level located at the middle of the band-gap of the GaAs capping layer [12]. Furthermore, the optical properties of InAs QDs are improved when they are embedded in asymmetric In 0.2 Ga 0.8 As wells [13].…”