High Mobility Two-Dimensional Bismuth Oxyselenide Single Crystals with Large Grain Size Grown by Reverse-Flow Chemical Vapor Deposition

Author(s):  
Xi Yang ◽  
Qi Zhang ◽  
Yingchao Song ◽  
Yansong Fan ◽  
Yuwen He ◽  
...  
2020 ◽  
Vol 32 (28) ◽  
pp. 2003751
Author(s):  
Yiyi Gu ◽  
Hui Cai ◽  
Jichen Dong ◽  
Yiling Yu ◽  
Anna N. Hoffman ◽  
...  

2020 ◽  
Vol 32 (19) ◽  
pp. 1906238 ◽  
Author(s):  
Yiyi Gu ◽  
Hui Cai ◽  
Jichen Dong ◽  
Yiling Yu ◽  
Anna N. Hoffman ◽  
...  

2021 ◽  
Vol 54 (4) ◽  
pp. 1011-1022
Author(s):  
Kongyang Yi ◽  
Donghua Liu ◽  
Xiaosong Chen ◽  
Jun Yang ◽  
Dapeng Wei ◽  
...  

ACS Nano ◽  
2011 ◽  
Vol 5 (9) ◽  
pp. 7198-7204 ◽  
Author(s):  
Michael E. Ramón ◽  
Aparna Gupta ◽  
Chris Corbet ◽  
Domingo A. Ferrer ◽  
Hema C. P. Movva ◽  
...  

2001 ◽  
Vol 664 ◽  
Author(s):  
Maribeth Swiatek ◽  
Jason K. Holt ◽  
Harry A. Atwater

ABSTRACTWe apply a rate-equation pair binding model of nucleation kinetics [1] to the nucleation of Si islands grown by hot-wire chemical vapor deposition on SiO2 substrates. Previously, we had demonstrated an increase in grain size of polycrystalline Si films with H2 dilution from 40 nm using 100 mTorr of 1% SiH4 in He to 85 nm with the addition of 20 mTorr H2. [2] This increase in grain size is attributed to atomic H etching of Si monomers rather than stable Si clusters during the early stages of nucleation, decreasing the nucleation density. Atomic force microscopy (AFM) measurements show that the nucleation density increases sublinearly with time at low coverage, implying a fast nucleation rate until a critical density is reached, after which grain growth begins. The nucleation density decreases with increasing H2 dilution (H2:SiH4), which is an effect of the etching mechanism, and with increasing temperature, due to enhanced Si monomer diffusivity on SiO2. From temperature-dependent measurements, we estimate the activation energy for surface diffusion of Si monomers on SiO2 to be 0.47 ± 0.09 eV. Simulations of the temperature-dependent supercritical cluster density lead to an estimated activation energy of 0.42 eV ± 0.01 eV and a surface diffusion coefficient prefactor of 0.1 ± 0.03 cm2/s. H2-dilution-dependent simulations of the supercritical cluster density show an approximately linear relationship between the H2 dilution and the etch rate of clusters.


1990 ◽  
Vol 5 (11) ◽  
pp. 2507-2514 ◽  
Author(s):  
A. T. Collins ◽  
M. Kamo ◽  
Y. Sato

Absorption and cathodoluminescence spectra have been recorded for single crystals of diamond and polycrystalline films of diamond, grown by microwave-assisted chemical vapor deposition (CVD) using methane and hydrogen. The investigation has been carried out to see to what extent the properties of CVD diamond are similar to those of conventional diamond, and to what extent they are unique. Studies have been made of the as-grown material, which has not been intentionally doped, and also samples that have been subjected to radiation damage and thermal annealing. The single crystals grown using methane concentrations of 0.5 to 1.0% exhibit bright blue “band A” emission and also intense edge emission, similar to the cathodoluminescence spectra of some natural type IIa diamonds. This implies that the crystals are relatively free from structural and chemical defects, a conclusion which is reinforced by the absence of any zero-phonon lines in the absorption spectra of crystals which have been subjected to radiation damage and annealing at 800 °C. Before radiation damage the spectrum does, however, reveal an absorption which increases progressively to higher energies, and which may be associated with sp2-bonded carbon. The Cathodoluminescence spectra after radiation damage indicate that the crystals contain some isolated nitrogen, and the detection of H3 luminescence, following thermal annealing at 800 °C, demonstrates for the first time that these samples contain small concentrations of nitrogen pairs. All of the polycrystalline films, grown using methane concentrations between 0.3 and 1.5%, have an absorption which increases progressively to higher energies, and which again is attributed to sp2-bonded carbon. This absorption is stronger in the films grown using higher methane concentrations. Films grown at a methane concentration of 0.3% also exhibit bright blue cathodoluminescence, although the edge emission is undetectably weak. The use of higher methane concentrations produces films with evidence in the cathodoluminescence spectra of nitrogen + vacancy and nitrogen + interstitial complexes, as well as optical centers unique to CVD diamond. One particular defect produces an emission and absorption line at 1.681 eV. By implanting conventional diamonds with 29Si ions it has been confirmed that this center involves silicon, and it has been shown that the 1.681 eV luminescence is relatively more intense in implanted diamonds which have a high concentration of isolated nitrogen.


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