Hydrogen in crystalline semiconductors

Häller, E. E.

doi:10.1088/0268-1242/6/2/001

Cited by 40 publications

(18 citation statements)

References 89 publications

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“…An explanation could be that there also exists a lifetime component, with a value in between the divacancy lifetime of ϳ330 ps and the bulk lifetime. This defect of monovacancy size would give a lifetime that in these two fits ͑473 K and 673 K annealings͒ becomes mixed with the lifetime 1 . It is however, very difficult to separate this smaller lifetime component from the lifetime spectrum, since the concentration of the defects having this positron lifetime component is small compared to the concentrations of the observed clusters or the divacancies.…”

Section: Brief Reports Physical Review B 78 033202 ͑2008͒mentioning

confidence: 99%

“…The supreme properties of silicon include a larger band gap, a stable oxide, and an extremely low surface-state density. 1,2 However, electron and hole mobilities are much higher in germanium than in silicon, which has lead to the use of strained Si 1−x Ge x heterostructures to increase mobility in modern transistors. [3][4][5] Even higher charge carrier mobilities could be pursued if transistors were built out of germanium, which is something that is attempted by many groups.…”

Section: Introductionmentioning

confidence: 99%

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Divacancy clustering in neutron-irradiated and annealedn-type germanium

et al. 2008

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We have studied the annealing of vacancy defects in neutron-irradiated germanium. After irradiation, the Sb-doped samples ͓͑Sb͒ = 1.5ϫ 10 15 cm −3 ͔ were annealed at 473, 673, and 773 K for 30 min. The positron lifetime was measured as a function of temperature ͑30-295 K͒. A lifetime component of 330 ps with no temperature dependence is observed in as-irradiated samples, identified as the positron lifetime in a neutral divacancy and indicating that the divacancy is stable at room temperature ͑RT͒. Annealing at 673 K resulted in an increase in the average positron lifetime, and in addition, the annealed samples further showed a larger lifetime component of 430 ps at RT, which is due to larger vacancy clusters. The average positron lifetime in the samples annealed at 473 K has a definite temperature dependence, suggesting that the divacancies become negative as the crystal recovers and the Fermi level moves upwards in the band gap. Annealing at 673 K, reduces the average lifetime and intensity of the defect component 2 at RT, indicating that the vacancy clusters have started to anneal. Negative divacancies are still present in the samples after this anneal. Annealing at 773 K is enough to remove all observable vacancy defects.

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Section: Brief Reports Physical Review B 78 033202 ͑2008͒mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Divacancy clustering in neutron-irradiated and annealedn-type germanium

et al. 2008

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“…The bandgap reopening effects were tentatively attributed to the formation of N-H complexes. The defect passivation by H in semiconductors is also expected, as being shown by a number of theoretical and experimental studies 25,26 .…”

Section: Post-growth Treatmentsmentioning

confidence: 72%

Room-temperature defect-engineered spin functionalities in Ga(In)NAs alloys

Puttisong¹

2016

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ii Cover image (front): -schematic representation of a spin polarized defect in a semiconductor.Copyright ©2014 Yuttapoom Puttisong, unless otherwise stated.Room temperature defect-engineered spin functionalities in Ga(In)NAs alloys Linköping studies in science and technology Dissertations No. 1607 Printed by LiU-Tryck, Linköping, Sweden, 2014 iii Abstract Semiconductor spintronics is one of the most interesting research fields that exploits both charge and spin properties for future photonics and electronic devices. Among many challenges of using spin in semiconductors, efficient generation of electron spin polarization at room temperature (RT) remains difficult. Recently, a new approach using defect-mediated spin filtering effect, employingGa -interstitial defects in Ga(In)NAs alloys, has been shown to turn the material into an efficient spin-polarized source capable of generating > 40% conduction electron spin polarization at RT without an application of external fields. In order to fully explore the defect-engineered spin functionalities, a better understanding and control of the spin filtering effects is required. This thesis work thus aims to advance our understanding, in terms of both physical and material insights, of the recently discovered spin filtering defects in Ga(In)NAs alloys. We have focused on the important issues of optimization and applications of the spin filtering effects.To improve spin filtering efficiency, important material and defect parameters must be addressed. Therefore, in Papers I-III formation of theGa defects in Ga(In)NAs alloys has been examined under different growth and post-growth treatment conditions, as well as in different structures. We found that theGa defects were the dominant and important nonradiative recombination centers in Ga(In)NAs epilayers and GaNAs/GaAs multiple quantum wells, independent of growth conditions and post-growth annealing. However, by varying growth and post-growth conditions, up to four configurations of theGa defects, exhibiting different hyperfine interaction (HFI) strengths between defect electron and nuclear (e-n) spins, have been found. This difference was attributed to different interstitial sites and/or complexes ofGa . Further studies focused on the effect of post-growth hydrogen (H) irradiation on the spin filtering effect. Beside the roles of H passivation of N resulting in bandgap reopening of the alloys, H treatment was shown to lead to complete quenching of the spin filtering effect, accompanied by strong suppression in the concentrations of theGa defects. We concluded that the observed effect was due to the passivation of theGa defects by H, most probably due to the formation of H-Ga complexes.Optimizing spin filtering efficiency also requires detailed knowledge of spin interactions at the defect centers. This issue was addressed in Papers IV and V. From both experimental and theoretical studies, we were able to conclude that the HFI between e-n spins at theGa defects led to e-n spin mixing, which degraded spin filtering efficie...

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“…On the other hand, n-type doping is much more difficult to achieve. The doping becomes less efficient for donor concentrations larger than about 3 × 10 18 cm −3 and the maximum electron concentration saturates at a level slightly above 10 19 cm −3 [37][38][39][40]. The maximum concentration does not depend on the dopant species or the method by which the dopants are introduced into the crystal.…”

Section: Maximum Doping Limits In Gaasmentioning

confidence: 99%

“…Hydrogen, lithium, and copper are known to passivate intentionally introduced dopants in semiconductors. Hydrogen has been an especially extensively studied impurity as it is a commonly used element in most semiconductor processing techniques and in all the growth techniques involving metal organic precursors [10]. In some cases hydrogen can be removed during postgrowth annealing.…”

Section: Introductionmentioning

confidence: 99%

Defects and Self-Compensation in Semiconductors

Walukiewicz

2006

Wide-Gap Chalcopyrites

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Defect formation and doping limits in semiconductors are discussed in terms of the amphoteric defect model (ADM). It is shown that the nature of defects, acceptor-like or donor-like, depends on the location of the Fermi energy relative to a common energy reference, the Fermi level-stabilization energy. The maximum free electron or hole concentration that can be achieved by doping is an intrinsic property of a given semiconductor and is fully determined by the location of the semiconductor band edges with respect to the same energy reference. The ADM provides a simple phenomenological rule that explains experimentally observed trends in free carrier saturation in a variety of semiconductor materials and their alloys. The predictions of a large enhancement of the maximum electron concentration in III-N-V alloys have been recently confirmed by experiment.

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Hydrogen in crystalline semiconductors

Cited by 40 publications

References 89 publications

Divacancy clustering in neutron-irradiated and annealedn-type germanium

Divacancy clustering in neutron-irradiated and annealedn-type germanium

Room-temperature defect-engineered spin functionalities in Ga(In)NAs alloys

Defects and Self-Compensation in Semiconductors

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