Composition Optimization and Phase Transformation of Si-Nanocrystal-Doped $\hbox{SiO}_{x}$ for Enhancing Luminescence From MOSLED

Near-infrared (NIR) photo- and electroluminescence (PL and EL) of Si nanocrystals buried in Si-rich SiO
_x
, film, and their correlation with the structural phase transformation and the varied oxygen composition of SiO
_x
, are investigated. By detuning the N
₂
O flowing ratio (Y
<sub>N

2

O</sub>
= [N
₂
O/(N
₂
O + SiH
₄
)] times 100%) from 93% to 80% during plasma-enhanced chemical vapor deposition growth, the oxygen composition ratio of the Si-rich SiO
_x
, can be adjusted from 1.64 to 0.88. The grazing incident X-ray diffraction and X-ray photoelectron spectroscopy spectra indicate that the SiO
_x
, transforms its structural phase from Si + SiO
₂
isomer to Si + SiO + SiO
₂
isomer. With O/Si ratio >1.24, the SiO
_x
, matrix becomes SiO
₂
isomer, whereas the SiO
_x
, structure approaches SiO phase at O/Si ratio that is nearly 1.0. The formation of SiO matrix in SiO
_x
, grown at Y
<sub>N

2

O</sub>
below 85% reduces the precipitated Si nanocrystal density from 2.8 times 10
¹⁸
to 7 times 10
¹⁶
cm
^-3
, and monotonically attenuates the NIR PL by one order of magnitude. Such a structural phase transformation from SiO
₂
to SiO in SiO
_x
with lower O/Si ratio causes the degradation in EL power conversion efficiency and external quantum efficiency (EQE). Maximum EL power of 0.5 muW and EQE of 0.06% are obtained from MOSLED made on SiO
_x
, with optimized O/Si ratio of 1.24.