Reduction of Tail State on Boron Doped Hydrogenated Amorphous Silicon Oxide Films Prepared at High Hydrogen Dilution

Abstract

In this report, we have investigated on the defect state of diborane (B2H6) doped wide bandgap hydrogenated amorphous silicon oxide (p-type a-SiO:H) films prepared using silane (SiH4), hydrogen (H2) and nitrous oxide (N2O) in a radio frequency (RF) plasma enhanced chemical vapor deposition (PECVD) system with different hydrogen dilutions. The films prepared with higher hydrogen dilution show lower Urbach energy (Eu), lower microstructure (R*), lower short and medium range disorder (omegaTO, Gamma(TO), I(TA)/I(TO), I(LA)/I(TO)), higher dark conductivity (sigma d) and higher refractive index (n) with high optical gap (Eg). Eu decreases from 248 meV to 153 meV, and R* decreases from 0.46 to 0.26, Raman peak omegaTO-TO mode position shifts from 480.24 to 483.28, GammaTO-full width half maximum of omegaTO decreases from 78.16 to 63.87, I(TA)/I(TO)-the ratio of integrated area of TA and TO mode decreases from 0.624 to 0.474, I(LA)/I(TO)-the ratio of integrated area of LA and TO mode deceases from 0.272 to 0.151, sigma d increases from 4.6 x 10(-7) S/cm to 1.1 x 10(-6) S/cm, n increases from 3.70 to 3.86. Reduced Nd, Eu and R* at wide Eg indicates that the films are more useful for solar cell window layer. Applying this layer to a single junction solar cell shows open circuit voltage (Voc) = 0.80 V, short circuit current density (Jsc) = 16.3 mA/cm2, fill factor (FF) = 72%, efficiency (eta) = 9.4%.

In and Ga Codoped ZnO Film as a Front Electrode for Thin Film Silicon Solar Cells

“…Up till now, despite the many advantages of thin film solar cells, their low efficiency is still a drawback that must be improved. In the recent years, much effort has been put in enhancing TFS-SC efficiency by many different ways [4][5][6]. One of these is to improve the quality of transparent conducting oxide (TCO) electrode layer, an integral part in the structure of thin film solar cells [7].…”

The Impact of the Micro-Structure within Passivated Layers on the Performance of the a-Si:H/c-Si Heterojunction Solar Cells

“…Initially, these values decrease as the treated power increases from 0 to 40 W, beyond which all values increase. Notably, the minimum values for I TA /I TO, ∆θ, and C were obtained at the treated power of 40 W. This suggests that a more ordered network corresponds to lower C values [16,19] Based on the information mentioned earlier, when the as-deposited a-Si:H(i) u goes post-hydrogen treatment, the following possible situations, as depicted in Fig may occur: Hydrogen atoms are effused (from hydrogen plasma) through the film su and into its bulk. During diffusion, hydrogen atoms with preferrI confirmed kinet ergy break weak Si-Si bonds (Figure 3a,b), followed by the deactivation of not on dangling bonds but also previously broken weak Si-Si bonds as well (Figure 3c).…”

“…The Raman spectra of the a-Si:H layers for different treated powers as a function of the wavenumber are illustrated in Figure 2. Figure 2 denotes the Si-Si Transverse Acoustical (TA) mode, Si-Si Longitudinal Acoustic (LA) mode, and Si-Si Transverse Optical (TO) mode, which correspond to the band at around 160 cm −1 , 310 cm −1 , and 480 cm −1 , respectively; while ∆θ TO (degrees) is the bond angle dispersion, referred from [16]. Marinov et al reported through a 216-atom model of a-Si (which was generated by the algorithm of Wooten, Winer, and Weaire) that the correlation length is associated with the vibrational mode localization state at different frequencies [17,18].…”

“…A high density of Si epitaxial growth must be prevented during a-Si:H deposition on the c-Si substrate. The a-Si:H is grown in a dense Energies 2023, 16, 6694 2 of 9 state, and the passivation property could be improved by the H 2 plasma treatment to avoid epitaxial formation. Descoeudres et al suggested that three short silane plasma steps with an additional short H 2 plasma treatment after each silane step can help suppress charge carrier recombination at surface dangling bonds on the c-Si surface [12].…”

High Performance of Solution-Processed Amorphous p-Channel Copper-Tin-Sulfur-Gallium Oxide Thin-Film Transistors by UV/O3 Photocuring

“…The conductivity and activation energy with respect to the UV/O 3 treatment time are shown in Figure e. According to the formula σ d ( T ) = σ 0 exp­(− E a / KT ), where σ d , σ 0 , E a , K , and T are the dark conductivity, pre-exponential factor, conductivity activation energy, Boltzmann constant, and absolute temperature, respectively, the lower E a of the 2 min UV/O 3 -treated CTSGO compared to that of the untreated one is attributed to the reduced sub-band-gap defects . The comparison of electrical conductivity and activation energy of the CTSGO films is summarized in Table S3.…”