The measurement of deep level states caused by misfit dislocations in InGaAs/GaAs grown on patterned GaAs substrates

Abstract

Rectangular Schottky diodes were fabricated on In0.06Ga0.94As grown by organometallic vapor phase epitaxy on GaAs substrates patterned with mesas. The density of α and β misfit dislocations at the strained-layer interface changed with the size of the rectangular mesas. Since all mesas (four sizes and two orientations) are processed simultaneously, all other defect concentrations are expected to remain constant in each diode. Scanning cathodoluminescence showed that the misfit dislocation density varied linearly with rectangle size. Deep-level transient spectroscopy showed that an n-type majority-carrier trap is present at 0.58 eV below the conduction band with a concentration that increases with increasing α-type misfit dislocation density. The β misfit dislocation density had no influence the deep level spectra, indicating that this trap is related to the cores of only α-type misfit dislocations. The capture rate trend corroborates the view that the trap is associated with the dislocation cores and not with isolated defects. Calculations indicate that the trap concentration is comparable to the concentration expected if all of the dislocation core atoms are electrically active.

Energy Levels and Electrical Activity of Dislocation Electron States in GaAs

“…Thus this result might be considered as an explicit manifestation of the energy levels of dislocations in GaAs, on the understanding that their sequence in the bandgap is inverted compared with that postulated formerly [1,3]. Taking into account the finding of Watson et al [9] and the present argumentation, we arrive at the following correspondence: ED1<=> α dislocations, HD1<=> β dislocations.…”

“…Watson et al [9] observed deep level states induced undoubtedly by misfit dislocations formed between InGaAs and GaAs layers grown by MOCVD technique. They could change the density of α and β dislocations separately by altering the size of rectangular mesas etched from the substrate.…”

Defect Creation in InGaAs/GaAs Multiple Quantum Wells – II. Optical Properties

“…The involved carrier states, mediating this loss mechanism were revealed to be associated with dislocation cores, and did not originate from spatially separated defect sites [7]. Our x-ray diffraction investigations [8] previously revealed distinct dependencies of the crystalline properties of InGaAs/GaAs multiple-quantum-well (MQW) structures on molecular beam epitaxy (MBE) growth conditions.…”

Electrical characterization of partially relaxed InxGa1−xAs/GaAs multiple quantum well structures

“…the linearly arrayed deep levels along the dislocation lines. 8,14 By contrast, if this broad DLTS spectrum is due to the interface traps between GaAs and InGaAs distributed in energy, the amplitude of the DLTS signal must saturate when the filling pulse time is large enough and the transient signal can show a logarithmic time dependence. 16 We have also confirmed that the amplitude of the broad DLTS signal becomes very small when the DLTS measurements are performed such that the filling pulse sweeps only two or three QWs from the top layer.…”

“…[3][4][5][6] So far most of the studies on the electrical properties of the strain-relaxed InGaAs/GaAs system have been concerned with single or double heterostructures. 7,8 The strain relaxation in MQWs or superlattices has been mostly studied by using x-ray diffraction, transmission electron microscopy, and photoluminescence techniques. 4,5,9,10 In this letter, we report on the electrical properties of partially relaxed In x Ga 1Ϫx As/GaAs MQW structures.…”