The DX Center: Evidence for Charge Capture Via an Excited Intermediate State

Theis, Thomas; Mooney, P. M.

doi:10.1557/proc-163-729

Cited by 26 publications

(9 citation statements)

References 34 publications

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“…The best fit to the data, using a model developed by Theis and Mooney [18], was for 0.23 eV < E, < 0.33 eV. Using our estimate that at 92 kbar Eo = 0.07 eV implies that the thermal emission energy was 0.3 eV< E, < 0.4 eV, thus confirming the large energy difference between the thermal and optical ionization energies.…”

Section: Discovery Of a DX Center In Inpsupporting

confidence: 71%

Far Infrared Spectroscopy of Semiconductors at Large Hydrostatic Pressures

Haller

Hsu

Wolk

1996

Physica Status Solidi (b)

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The combination of high resolution far infrared spectroscopy and large hydrostatic pressures produced by diamond anvil cells (DAC) offers a unique approach to the study of dopants, defects, and bandstructure related properties of semiconductors. The problem of small optical throughputs typical of DACs has been solved. Using this unique tool, we have obtained several new results, including the discovery of a local vibrational mode of the DX center in GaAs: Si and the demonstration that the DX center is a negativeU defect. We have also discovered the first evidence of DX centers in InP and studied the ground to bound excited state transitions of shallow impurities in GaAs at pressures at which GaAs is an indirect bandgap semiconductor with its conduction band minimum near the X symmetry point. I ) Mailstop 2-200,

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Section: Discovery Of a DX Center In Inpsupporting

confidence: 71%

Far Infrared Spectroscopy of Semiconductors at Large Hydrostatic Pressures

Haller

Hsu

Wolk

1996

Physica Status Solidi (b)

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“…The existence of this deep state was predicted much earlier from tight-binding calculations [31]. It has been suggested that the intermediate D 0 state could be the A 1 state [22]. This issue is however not yet resolved.…”

Section: The Dx-center Most Donors In Gaas Likementioning

confidence: 92%

“…The donor atom moves in the ͗111͘ direction to an interstitial site and leaves a vacancy at the lattice site. There is experimental evidence that the capture of the electrons is a two-step process mediated via a neutral D 0 state, associated with the donor on the substitutional lattice site [22]. In addition it was found that the photo-ionization of the DX center is also a two-step process [23].…”

Section: The Dx-center Most Donors In Gaas Likementioning

confidence: 99%

Spatial correlation effects in the charged impurity distribution on the electronic properties of δ‐doped structures

Stadt

Koenraad²,

Shi

et al. 2003

Physica Status Solidi (b)

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Dedicated by the coauthors to Professor Jozef T. Devreese on the occasion of his 65th birthday PACS 71.55. Eq, 73.50.Dn, 73.63.Hs In this paper we will show that the δ-doped GaAs/AlGaAs/GaAs quantum barrier is an ideal system to study deep centers in narrow doping layers with high doping density. By varying the Al content in the barrier, the distance between the Fermi-level and the deep level can be tuned and therefore the number of populated states. By applying hydrostatic pressure this number can be further increased. Our measurements show that in these δ-doped barrier structures electrons are trapped under hydrostatic pressure and that the quantum mobility is enhanced. This mobility enhancement can be explained by MC calculations which include the effect of the spatial correlation of the charge distribution when the deep state is the DX center and has a negative charge state. The fact that we do not observe a PPC effect or a significant change in the mobility after illumination at high pressure suggest that the Fermi-level is pinned by a non-metastable deep state like the A 1 state or that the DX center is modified.1 Introduction The idea of positioning individual atoms on a surface is very appealing and has many futuristic applications other than a 5-atom font size [1]. Using STM atoms can be moved around and placed on the surface in any configuration. Thus we can in principle create an artificial lattice. Especially in the semiconductor field this is an attractive concept because ordering of the doping atoms is expected to increase the electrical activity [2], reduce dopant fluctuations [3] and increase the carrier mobility [4]. However for practical applications too many atoms are involved thus the ordering of impurity atoms should be self-assembling. This can be accomplished by using a modified substrate surface, which has sites to which doping atoms preferentially go. At high enough growth temperatures the impurity atoms are allowed to diffuse to these sites. This technique has been applied to reconstructed surfaces [2,5] and misaligned substrates [6]. Most of these studies were concerned with structural properties and some with the consequences of such ordering on the electronic properties [7]. These growth studies are however difficult and require a lot of samples. There is fortunately a different approach to study spatial correlation effects by obtaining ordering in the charge distribution of randomly ordered impurity atoms. This ordering cannot be as large as a full spatial ordering introduced during growth, but the degree of ordering can be changed within one structure. Such ordering in the charge distribution can be obtained using the DX state associated with the Si donor in GaAs. By applying hydrostatic pressure electrons are trapped in these states. In current models this donor state is either neutral [8] or negatively [9] charged. Thus when DX centers are populated we have a so-called multi-valence system with either positively charged and

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“…A careful analysis of the Hall data in Al,Gal-.As:Si resulted in a good fit with either the DXor the Do state as a ground state but a reconciliation with capture and emission data preferred the DXstate as the ground state [3]. The difficulty in discriminating between two states within a thermal equilibrium experiment like the above Hall experiment consists in an unavoidable charge compensation due to the amphoteric nature of the Si atom 131.…”

Section: Introductionmentioning

confidence: 91%