Admittance spectroscopy on buried GaSb junctions due to defect distribution in GaAs/GaSb metalorganic vapor phase epitaxy heterostructures

Abstract

Electrical and interfacial properties of GaAs/GaSb metal-organic vapour phase epitaxy heterostructures J. Appl. Phys. 113, 043719 (2013); 10.1063/1.4789603 Microstructural defects in metalorganic vapor phase epitaxy of relaxed, graded InGaP: Branch defect origins and engineering J.Influence of growth rate on charge transport in GaSb homojunctions prepared by metalorganic vapor phase epitaxy

Electrical characterization of a buried GaSb p‐n junction controlled by native defects

“…Current‐voltage (I‐V) characteristics, performed after the removal of the GaAs layer, demonstrated, in all the investigated samples, the formation of the buried junctions with good rectification properties : in this work the attention will be focused on two samples, labelled as 19‐630 and 20‐660, the only ones where AS investigation revealed the double acceptor levels . Moreover on these samples capacitance‐voltage (C‐V) investigation showed the widest thicknesses of the space charge region (SCR), around 1–2 μm, and the lowest apparent free carrier densities, below 10 16 cm −3 , with respect to those measured in the other junctions . The samples differ for the Zn doping of the overgrown GaAs and for details of the post‐growth annealing process; in particular, the sample 19‐630, characterized by a Zn doping of the GaAs layer of 1 × 10 19 cm −3 , was submitted to a post‐grown annealing of 2 h at a temperature of 630 °C; while the sample 20‐660 was obtained by a 1 × 10 20 cm −3 Zn‐doped GaAs layer and treated for 2 h at 660 °C.…”

“…These results, widely discussed in Refs. and , appeared consistent with the hypothesis of an enhanced density of unintentional stoichiometric acceptors in proximity of the top surface, which governs the conductivity sign of GaSb up to about 1 μm beyond the Zn penetration depth. Therefore, the p‐n homojunctions resulted not to be ascribable to Zn diffusion.…”

“…13 it has been supposed that the Zn doping level and the annealing process influence the diffusion of these defects inside the substrate, even by changing the doping symmetry of the junction, from a p + ‐ n junction to a p – ‐ n one, and by making it graded and quite symmetric . In samples where these extreme conditions are reached, admittance spectroscopy (AS) pointed out two levels with energies comparable to those of the double native acceptor typical of GaSb, the antisite defect Ga Sb . This result permitted to identify the antisite defect as the unintentional acceptor responsible of the p ‐type conversion of the GaSb conductivity beyond the Zn diffusion front.…”

“…In Refs. and the build‐up of the buried junction has been described in the light of the mechanisms of Zn diffusion and Ga self‐diffusion in GaSb, widely explored in the recent past by Bracht and coworkers , by assigning to Ga vacancies a key role.…”

“…Current‐voltage (I‐V) characteristics, performed after the removal of the GaAs layer, demonstrated, in all the investigated samples, the formation of the buried junctions with good rectification properties : in this work the attention will be focused on two samples, labelled as 19‐630 and 20‐660, the only ones where AS investigation revealed the double acceptor levels . Moreover on these samples capacitance‐voltage (C‐V) investigation showed the widest thicknesses of the space charge region (SCR), around 1–2 μm, and the lowest apparent free carrier densities, below 10 16 cm −3 , with respect to those measured in the other junctions .…”