Physical nature of the InP near-surface defect acceptor and donor states

1987 ◽  
Vol 36 (11) ◽  
pp. 5914-5919 ◽  
Author(s):  
K. Ken Chin ◽  
R. Cao ◽  
T. Kendelewicz ◽  
K. Miyano ◽  
J. -J. Yeh ◽  
...  
1986 ◽  
Vol 77 ◽  
Author(s):  
K. K. Chin ◽  
R. Cao ◽  
T. Kendelewicz ◽  
K. Miyano ◽  
J. J. Yeh ◽  
...  

ABSTRACTThe physical nature of the InP near-surface defect acceptor and donor states are studied by using photoemission spectroscopy. It is found that the In/n-InP(110) interface band bending does not start until the In coverage reaches about 0.3 monolayer (ML), while the In/p-InP(110) band bending is almost saturated at 0.3 ML. The annealing effect on the band bending of clean cleaved n-and p-type InP(llO) surfaces is also studied. It is found that annealing of the clean surface creates an irreversible band bending effect on the p-InP(110), but the n-InP(110) almost does not show any band bending after low temperature annealing. Based on these two striking differences in the band bending behavior of n- and p-type InP, it is proposed that the physical nature of InP near-surface defect acceptor and donor levels may be different and that phosphorus vacancies are the cause of p-InP surface Fermi level pinning.


2020 ◽  
Vol 12 (20) ◽  
pp. 3350
Author(s):  
Shashwat Shukla ◽  
Valentyn Tolpekin ◽  
Shashi Kumar ◽  
Alfred Stein

The Moon has a large potential for space exploration and mining valuable resources. In particular, 3He provides rich sources of non-radioactive fusion fuel to fulfill cislunar and Earth’s energy demands, if found economically feasible. The present study focuses on developing advanced techniques to prospect 3He resources on the Moon from multi-sensor remote sensing perspectives. It characterizes optical changes in regolith materials due to space weathering as a new retention parameter and introduces a novel machine learning inversion model for retrieving the physical properties of the regolith. Our analysis suggests that the reddening of the soil predominantly governs the retention, along with attenuated mafic band depths. Moreover, semi-variograms show that the spatial variability of 3He is aligned with the episodic weathering events at different timescales. We also observed that pyroclastic regoliths with high dielectric constant and increased surface scattering mechanisms exhibited a 3He abundant region. For ejecta cover, the retention was weakly associated with the dielectric contrast and a circular polarization ratio (CPR), mainly because of the 3He-deficient nature of the regolith. Furthermore, cross-variograms revealed inherent cyclicity attributed to the sequential process of weathering effects. Our study provides new insights into the physical nature and near-surface alterations of lunar regoliths that influence the spatial distribution and retention of solar wind implanted 3He.


2002 ◽  
Vol 743 ◽  
Author(s):  
Hideki Hasegawa ◽  
Tamotsu Hashizume

ABSTRACTThis paper reviews the authors′ recent efforts to clarify the properties of electronic states near surfaces of GaN and AlGaN by using variousin-situandex-situcharacterization techniques, including UHV contact-less C-V, photoluminescence surface state spectroscopy (PLS3), cathode luminescence in-depth spectroscopy (CLIS),and gateless FET techniques that have been developed by the authors’ group.As a result, a model including a U-shaped surface state continuum, having a particular charge neutrality level, combined with frequent appearance of near-surface N-vacancy related deep donor states having a discrete level at Ec - 0.37eV is proposed as a unified model that can explain large gate leakage currents and current collapse in AlGaN/GaN HFETs. Hydrogen plasma treatment and SiO2deposition increase N-vacancy related deep donors. Reasonably good surface passivation can be achieved by ECR-plasma SiNx films and by ECR-plasma oxidized Al2O3films both combined with ECR N2plasma treatment.


Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 599 ◽  
Author(s):  
Vigilio Fontanari ◽  
Alberto Molinari ◽  
Michelangelo Marini ◽  
Wolfgang Pahl ◽  
Matteo Benedetti

The present paper is aimed at investigating the effect of porosity and microstructure on tooth root bending fatigue of small-module spur gears produced by powder metallurgy (P/M). Specifically, three steel variants differing in powder composition and alloying route were subjected either to case-hardening or sinter-hardening. The obtained results were interpreted in light of microstructural and fractographic inspections. On the basis of the Murakami a r e a method, it was found that fatigue strength is mainly dictated by the largest near-surface defect and by the hardness of the softest microstructural constituent. Owing to the very complicated shape of the critical pore, it was found that its maximum Feret diameter is the geometrical parameter that best captures the detrimental effect on fatigue.


2012 ◽  
Vol 157-158 ◽  
pp. 7-10
Author(s):  
Chao Lu ◽  
Guo Chen ◽  
Xin Wang

Aim at the problem of near surface blind area in ultrasonic TOFD technique, a new testing mode combined to ultrasound time of flight diffraction-reflection(TOFDR) and the three-fold reflected(TOFDW) based on secondary longitudinal waves was put forward. Through analysis the transmission characteristics of TOFDR and TOFDW, the two modes of the detection principle were illustrated, and discussed the ability in near surface detection of the two methods. Finally through the detecting artificial defects detection, the signal and image characteristics and detection sensitivity under the modified detection mode were studied. The artificial defect with buried depth of 1mm can be effectively detected from the D-scan image by the combined TOFDR and TOFDW methods.


2013 ◽  
Vol 103 (14) ◽  
pp. 141601 ◽  
Author(s):  
Prashun Gorai ◽  
Alice G. Hollister ◽  
Edmund G. Seebauer

1999 ◽  
Vol 28 (3) ◽  
pp. 308-313 ◽  
Author(s):  
A. P. Young ◽  
J. Schäfer ◽  
L. J. Brillson ◽  
Y. Yang ◽  
S. H. Xu ◽  
...  

2003 ◽  
Vol 431-432 ◽  
pp. 301-306 ◽  
Author(s):  
A. Rockett ◽  
D. Liao ◽  
J.T. Heath ◽  
J.D. Cohen ◽  
Y.M. Strzhemechny ◽  
...  
Keyword(s):  

1998 ◽  
Vol 510 ◽  
Author(s):  
Nikolai A. Yarykin

AbstractThe distribution of hydrogen penetrated into n-type silicon crystals during chemical etching is described mathematically. The depth profiles of the defects passivated by hydrogen and of defect-hydrogen complexes are also calculated. Comparison with the experimental data obtained on the silicon crystals with radiation defects and doped with transition metals reveals that the model adequately describes the processes in the crystal. By comparing the parameters of the depth profiles, the passivation and appearance of different defects are shown to be caused by the same diffusing species. The number of hydrogen atoms contained in the defect-hydrogen complexes and the distance of the hydrogen-defect interaction are determined from the characteristic length of the defect distribution. The diffusion length (1 to 3 νm) and diffusivity (> 5-10−9 cm2s−1) of hydrogen at room temperature are found indirectly based on the other defect distribution.


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