Si Nanocrystal Embedded SiC MOS Light Emitting Diodes
Date Issued
2010
Date
2010
Author(s)
Chen, Chun-Chieh
Abstract
We demonstrate the deposition and characterization of silicon-rich and carbon-rich amorphous silicon carbide films by plasma-enhanced chemical vapor deposition (PECVD). The oxygen quantity reduces from 33.9 to 9.2% utilizing Ar purge to eliminate the residual oxygen gas in the chamber of PECVD. From the XPS analysis, it has higher composition ratio x, lower ratio of Igraphite-like sp2 C-C /Idiamond-like sp3 C-C with Ar purge result in lower resistivity and reducing electronic defects under the some fluence ratio g. From the PL spectrum and analysis of FTIR the peak wavelength blue shift with and the rocking modes of Si-CH3 shifts from 896 to 922 cm-1 with the fluence ratio, respectively, due to Carbon atoms increases in the a-SixC1-x films. After annealing treatment, the thickness decreases and crack due to the structural relaxation and lattice mismatch, respectively. The rS and Rc increase from 3.18×106 to 4.8×108 (Ω/□) and 2.55×105 to 1.97×107 (Ω) surveyed by Transmission-Line-Model (TLM) as increasing the fluence ratio g = 70 to 90%. We prepare the Al/p-Si/i-SiC with Si-nc/n-SiC/ITO device with the different depositing substrate temperature. From the TEM result, the average diameter of the Si-nc is 2.7±0.2 nm embedded in silicon-rich SiC matrix. By combination annealing treatment under 1050oC for 30 min and PH3 doping, the resistivity decrease from 3.48×10-3 to 8.98×10-5 Ω-cm with increasing the ratio of PH3/(SiH4+CH4+SiH3CH3+Ar) from 0.6% to 5%. As depositing substrate temperature increase from 300oC to 650oC, the optical output power, power conversion ratio (PCR), and external quantum efficiency (EQE) increase from 5.4 nW to 22.7 nW, 1.6×10-8 to 7.1×10-8, and 1.6×10-7 to 2.5×10-7, respectively. It is due to the stable composition ratio x as function of vertical deep in the SixC1-x film, preventing the SixC1-x film from the incorporation of oxygen, and making the SixC1-x film crystallize after annealingtreatment, respectively. The result of the electroluminescence (EL) spectrum show the peak position is 570 nm which agree with the EL pattern.
Subjects
Amorphous Silicon Carbide
PECVD
Sheet Resistivity
Silicon Nanocrystal
EQE
MOS LED
Type
thesis
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