title: 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%.
authors.affiliation: College of Information and Communication Engineering, Sungkyunkwan University, Suwon, 440-746, Korea.
authors.forename: Jinjoo
authors.initials: J
authors.lastname: Park
authors.forename: S M
authors.initials: SM
authors.lastname: Iftiquar
authors.forename: Sunwha
authors.initials: S
authors.lastname: Lee
authors.forename: Hyeongsik
authors.initials: H
authors.lastname: Park
authors.forename: Chonghoon
authors.initials: C
authors.lastname: Shin
authors.forename: Junhee
authors.initials: J
authors.lastname: Jung
authors.forename: Youn-Jung
authors.initials: YJ
authors.lastname: Lee
authors.forename: Nagarajan
authors.initials: N
authors.lastname: Balaji
authors.forename: Junsin
authors.initials: J
authors.lastname: Yi