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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.


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Conventional DLTS scans for each MBE grown AlGaAs sample.
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Figure 1: Conventional DLTS scans for each MBE grown AlGaAs sample.

Mentions: DLTS spectra shown in Figure 1 are obtained using a rate window of 50 Hz, quiescent reverse bias Vr = -3 V, filling pulse Vp = -0.5 V and filling pulse duration tp = 1 ms. Three and four hole traps are observed in the samples grown on (100) plane for doping concentrations of 1 × 1016 and 3 × 1016 cm-3, respectively. In addition to two hole traps, two electron traps are observed in the sample doped to 1 × 1017 cm-3. Whereas for the (311)A orientation, five, two and one hole traps have been detected in samples doped with 1 × 1016, 3 × 1016 and 1 × 1017 cm-3, respectively. In contrast with the (100) samples no electron emitting levels were found in (311)A samples. For convenience holes traps are labelled as HA, HB, HC, HD, HE and HF, in NU1362, NU1363, NU1364, NU1365, NU1366 and NU1367, respectively. The digits correspond to a particular trap in each sample as referred to in Figure 2 and Table 1. Similarly, the detected electron traps are named as E1 and E2.


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)

Conventional DLTS scans for each MBE grown AlGaAs sample.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: Conventional DLTS scans for each MBE grown AlGaAs sample.
Mentions: DLTS spectra shown in Figure 1 are obtained using a rate window of 50 Hz, quiescent reverse bias Vr = -3 V, filling pulse Vp = -0.5 V and filling pulse duration tp = 1 ms. Three and four hole traps are observed in the samples grown on (100) plane for doping concentrations of 1 × 1016 and 3 × 1016 cm-3, respectively. In addition to two hole traps, two electron traps are observed in the sample doped to 1 × 1017 cm-3. Whereas for the (311)A orientation, five, two and one hole traps have been detected in samples doped with 1 × 1016, 3 × 1016 and 1 × 1017 cm-3, respectively. In contrast with the (100) samples no electron emitting levels were found in (311)A samples. For convenience holes traps are labelled as HA, HB, HC, HD, HE and HF, in NU1362, NU1363, NU1364, NU1365, NU1366 and NU1367, respectively. The digits correspond to a particular trap in each sample as referred to in Figure 2 and Table 1. Similarly, the detected electron traps are named as E1 and E2.

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