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Electrical characterisation of deep level defects in Be-doped AlGaAs grown on (100) and (311)A GaAs substrates by MBE.

Mari RH, Shafi M, Aziz M, Khatab A, Taylor D, Henini M - Nanoscale Res Lett (2011)

Bottom Line: However, despite many efforts hole mobilities in Be-doped structures grown on (100) GaAs substrate remained considerably lower than those obtained by growing on (311)A oriented surface using silicon as p-type dopant.It was observed that with increasing the Be-doping concentration from 1 × 1016 to 1 × 1017 cm-3 the number of detected electrically active defects decreases for samples grown on (311)A substrate, whereas, it increases for (100) orientated samples.From these findings it is expected that mobilities of 2DHGs in Be-doped GaAs-GaAlAs devices grown on (311)A should be higher than those on (100).

View Article: PubMed Central - HTML - PubMed

Affiliation: Nottingham Nanotechnology and Nanoscience Center, University of Nottingham, Nottingham NG7 2RD, UK. mohamed.henini@nottingham.ac.uk.

ABSTRACT
The growth of high mobility two-dimensional hole gases (2DHGs) using GaAs-GaAlAs heterostructures has been the subject of many investigations. However, despite many efforts hole mobilities in Be-doped structures grown on (100) GaAs substrate remained considerably lower than those obtained by growing on (311)A oriented surface using silicon as p-type dopant. In this study we will report on the properties of hole traps in a set of p-type Be-doped Al0.29Ga0.71As samples grown by molecular beam epitaxy on (100) and (311)A GaAs substrates using deep level transient spectroscopy (DLTS) technique. In addition, the effect of the level of Be-doping concentration on the hole deep traps is investigated. It was observed that with increasing the Be-doping concentration from 1 × 1016 to 1 × 1017 cm-3 the number of detected electrically active defects decreases for samples grown on (311)A substrate, whereas, it increases for (100) orientated samples. The DLTS measurements also reveal that the activation energies of traps detected in (311)A are lower than those in (100). From these findings it is expected that mobilities of 2DHGs in Be-doped GaAs-GaAlAs devices grown on (311)A should be higher than those on (100).

No MeSH data available.


Related in: MedlinePlus

Traps showing electric field-dependent emission rates. The data are analysed using Poole-Frenkel model.
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Figure 3: Traps showing electric field-dependent emission rates. The data are analysed using Poole-Frenkel model.

Mentions: For analysis purposes, the trap energies are compared with published data. It is found that the traps HA2 and HE2 (0.145 ± 0.006 and 0.130 ± 0.01 eV), respectively, have almost the same activation energy as that of H1 (0.14 eV) [11], but seem to be different in nature than that of H1. For example the capture cross-section of H1 [11] was found to be temperature-dependent, whereas in this study the capture cross-sections of HA2 and HE2 are temperature insensitive. However, HA2 shows electric field-dependent emission rate and obeys the Poole-Frenkel model (Figure 3) with constant αPF = 10.5 × 10-5 eV(cm/V)1/2 whereas, the carrier emission rate of HE2 are electric field-independent.


Electrical characterisation of deep level defects in Be-doped AlGaAs grown on (100) and (311)A GaAs substrates by MBE.

Mari RH, Shafi M, Aziz M, Khatab A, Taylor D, Henini M - Nanoscale Res Lett (2011)

Traps showing electric field-dependent emission rates. The data are analysed using Poole-Frenkel model.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211234&req=5

Figure 3: Traps showing electric field-dependent emission rates. The data are analysed using Poole-Frenkel model.
Mentions: For analysis purposes, the trap energies are compared with published data. It is found that the traps HA2 and HE2 (0.145 ± 0.006 and 0.130 ± 0.01 eV), respectively, have almost the same activation energy as that of H1 (0.14 eV) [11], but seem to be different in nature than that of H1. For example the capture cross-section of H1 [11] was found to be temperature-dependent, whereas in this study the capture cross-sections of HA2 and HE2 are temperature insensitive. However, HA2 shows electric field-dependent emission rate and obeys the Poole-Frenkel model (Figure 3) with constant αPF = 10.5 × 10-5 eV(cm/V)1/2 whereas, the carrier emission rate of HE2 are electric field-independent.

Bottom Line: However, despite many efforts hole mobilities in Be-doped structures grown on (100) GaAs substrate remained considerably lower than those obtained by growing on (311)A oriented surface using silicon as p-type dopant.It was observed that with increasing the Be-doping concentration from 1 × 1016 to 1 × 1017 cm-3 the number of detected electrically active defects decreases for samples grown on (311)A substrate, whereas, it increases for (100) orientated samples.From these findings it is expected that mobilities of 2DHGs in Be-doped GaAs-GaAlAs devices grown on (311)A should be higher than those on (100).

View Article: PubMed Central - HTML - PubMed

Affiliation: Nottingham Nanotechnology and Nanoscience Center, University of Nottingham, Nottingham NG7 2RD, UK. mohamed.henini@nottingham.ac.uk.

ABSTRACT
The growth of high mobility two-dimensional hole gases (2DHGs) using GaAs-GaAlAs heterostructures has been the subject of many investigations. However, despite many efforts hole mobilities in Be-doped structures grown on (100) GaAs substrate remained considerably lower than those obtained by growing on (311)A oriented surface using silicon as p-type dopant. In this study we will report on the properties of hole traps in a set of p-type Be-doped Al0.29Ga0.71As samples grown by molecular beam epitaxy on (100) and (311)A GaAs substrates using deep level transient spectroscopy (DLTS) technique. In addition, the effect of the level of Be-doping concentration on the hole deep traps is investigated. It was observed that with increasing the Be-doping concentration from 1 × 1016 to 1 × 1017 cm-3 the number of detected electrically active defects decreases for samples grown on (311)A substrate, whereas, it increases for (100) orientated samples. The DLTS measurements also reveal that the activation energies of traps detected in (311)A are lower than those in (100). From these findings it is expected that mobilities of 2DHGs in Be-doped GaAs-GaAlAs devices grown on (311)A should be higher than those on (100).

No MeSH data available.


Related in: MedlinePlus