Capture barrier and the ionization entropy of the D
 X center in Se-doped AlxGa1−xAs

Deep-level transient spectroscopy (DLTS) and constant-capacitance DLTS (CC-DLTS) techniques have been used to investigate selenium-related DX centers in AlGaAs alloys. The value of the thermal activation energy obtained by both techniques was the same (0.21 eV); however, experimental curves show some important differences. While CC-DLTS curves show only one peak, which reveals that there exists only one DX center in Se-doped AlGaAs, in DLTS curves it is possible to resolve up to two peaks lying at a lower temperature than the one observed by CC-DLTS. This disagreement may be due to the fact that DLTS measurements are strongly affected by refilling effects which occur in the edge zone of the space-charge region during capacitance transients performed at constant voltage. These effects accelerate the capacitance transients and can lead to too high thermal-emission rates. In contrast, these effects do not affect CC-DLTS curves, because in constant-capacitance voltage transients the edge of the space-charge region remains unchanged and refilling effects do not take place. These effects are rather important on DX levels because they exhibit thermally activated capture cross sections and very low ionization factors at the experimental temperatures and, therefore, capture processes are slow and their time constants can be similar to those of the emission processes.

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Influence of refilling effects on deep-level transient spectroscopy measurements in Se-doped AlxGa1−xAs

Enríquez

Dueñas

Barbolla

et al. 1992

Journal of Applied Physics

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Characterization of traps in InAlN by optically and thermally stimulated deep level defect spectroscopies

Farzana

Foronda

Jackson

et al. 2018

Journal of Applied Physics

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Deep level transient spectroscopy (DLTS) and deep level optical spectroscopy (DLOS) were used to characterize defect states throughout the bandgap of unintentionally-doped InxAl1−xN grown by metal organic chemical vapor deposition for x = 0.18 (nominally lattice-matched) and x = 0.15 compositions. DLTS revealed broad peaks with energy levels of EC − 0.23 eV and 0.38 eV for In0.18Al0.82N and In0.15Al0.85N, respectively, tracking the difference in their conduction band minima [S. Schulz et al., Appl. Phys. Express 6, 121001 (2013)]. Capture kinetics studies revealed logarithmic filling behavior, which with the broad peaks, implies that an extended defect source is likely, consistent with threading dislocation densities (TDD) of ∼1 × 109 cm−2 measured for both structures. However, the trap concentration did not track the detailed TDD variation but instead followed the background oxygen content, which varied between 1.2 × 1018 cm−3 and 1.8 × 1018 cm−3 for the samples. Taken together with the logarithmic capture kinetics, this implies that dislocation-oxygen complexes could be the source for this trap. In spite of the high oxygen content in the samples, this state did not reveal DX-like behavior, supporting the assertion of an oxygen-dislocation complex as its likely source. DLOS also revealed additional states at EC − 1.63 eV, 2.09 eV, and 3.59 eV for In0.18Al0.82N and analogous states at EC − 1.70 eV, 2.70 eV, and 3.90 eV within In0.15Al0.85N. Lighted capacitance-voltage measurements indicated that the near mid-gap (EC − 2.09 eV and 2.70 eV) and near valence band (EC − 3.59 eV and 3.90 eV) states are their primary sources for carrier compensation.

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DX centre characterization in Se-doped AlGaAs under hydrostatic pressure

Calleja¹,

García²,

Romero³

et al. 1992

Semicond. Sci. Technol.

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Se-related DX centres in AlGaAs alloys have been characterized by deep-level transient spectroscopy techniques under hydrostatic pressure. The thermai-emission energy, E. = 0.24 0.02 eV, i s constant throughout the alloy range considered (0.29 < x < 0.77). and independent of the applied pressure. The thermai-capture barrier energy follows a V-shaped curve as a function of the alloy composition. with E , , , , = 0.13 eV for Ai compositions around 38 %. where the Se-DX centre electron occupancy is a maximum. Emission spectra show.up to three peaks generated by three discrete emission rates. Their pressure dependence suggests the existence of three close discrete DX levels originating from changes of the donor local environment. These resuits'confirm the model proposed by Chadi and Chang for Se-related DX centres (group-VI donors). As compared with the Si-DX centre properties quantitative differences originate from a shallower energy position of Se-DX centres in the gap, owing to smaller values of the tnermai emission and capture barriers, 200 meV and 70 meV lower, respectiveiy.

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Capture barrier and the ionization entropy of the D X center in Se-doped AlxGa1−xAs

Cited by 4 publications

References 17 publications

Influence of refilling effects on deep-level transient spectroscopy measurements in Se-doped AlxGa1−xAs

Influence of refilling effects on deep-level transient spectroscopy measurements in Se-doped AlxGa1−xAs

Characterization of traps in InAlN by optically and thermally stimulated deep level defect spectroscopies

DX centre characterization in Se-doped AlGaAs under hydrostatic pressure

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