Xuemin Tian

Boron-incorporated amorphous carbon films deposited by pulsed laser deposition

Boron-incorporated carbon films (a-C(B)) were deposited on a silicon substrate by pulsed laser deposition (PLD) of a graphite target at room temperature. The boron content was determined by X-ray photoelectron spectroscopy (XPS) to be in the range of 0.2–1.7 at.% in the films. These films were confirmed to be p-type due to the formation of a heterojunction between the a-C(B) carbon film and silicon substrate. The devices of C(B)/n-Si configuration show a maximum [open-circuit voltage] Voc=0.25 V, and [short-circuit current density] Jsc=2.1 mA/cm2 under illumination (AM 1.5, 100 mW/cm2).

Influence of deposition parameters on the structural, optical and electrical properties of amorphous carbon and amorphous carbon nitride films grown by pulsed laser deposition using camphoric carbon target

The role of laser fluence (LF) and target to substrate distance (TSD) on the surface morphology, deposition rate, composition, structural, optical and electrical properties of amorphous carbon (a-C) and amorphous carbon nitride (a-CN x ) films deposited by Xe-Cl excimer pulsed laser deposition is reported. At fixed TSD, the surface roughness, particle density and deposition rate increase, whereas the particle size decreases with higher LF. When the LF is fixed, TSD decreases resulting in an increase in the irregular small particle size, particle density, surfaces roughness and deposition rate. We found that the amorphous structure of a-C and a-CN x films is strongly dependent on the LF and TSD. The a-CN x films with high deposition rate have relatively high nitrogen content and high electrical resistivity.

Photovoltaic characteristics of boron doped amorphous carbon films deposited by pulsed laser deposition using graphite target

This paper reports on the successful deposition of boron (B) doped carbon films (p-C(B)) and fabrication of p-C(B)/n-Si solar cells by pulsed laser deposition (PLD) technique at room temperature using graphite target. The B content in the film was determined by X-ray photoelectron spectroscopy (XPS) to be in the range of 0.2-1.7 atomic percentage. The photovoltaic values of the device, a maximum open circuit voltage, V oc = 250 m V and short circuit current density, J sc = 2.113 mA/cm 2 were obtained, when exposed to AM 1.5 illumination (100 mW/cm 2 , 25°C). The maximum energy conversion efficiency was found tentatively to be about, η = 0.2%, together with the fill factor, FF = 45%. In this paper, the dependence of the B content on electrical and optical properties of the p-C(B) films and the photovoltaic characteristic of the p-C(B)/n-Si structure photovoltaic solar cells are discussed.

Diamond Synthesized at Room Temperature by Pulsed Laser Deposition in Vacuum

Here we show that diamond particles were formed on (100) silicon substrates by XeCl (308 nm, 20 ns) laser ablation using a urea doped camphoric carbon target in vacuum. The substrate temperature and the pressure were kept at room temperature (25°C) and (4–5)×10-5 Torr, respectively without feeding any gases during the deposition. Raman spectroscopy analysis confirmed the diamond cubic structure of the crystals by the presence of a sharp peak at 1337.8 cm-1. One broad peak is also observed in the spectra centered at 1550 cm-1, which is attributed to the G-peak in the film.

Properties of p-C:B films using graphite target and fabrication of p-C:B/n-Si heterojunction solar cells

This paper reports on the successful deposition of boron (B)-doped p-type amorphous carbon (p-C:B) films, and fabrication of p-C:B/n-Si by pulsed laser deposition (PLD) using graphite target. The cells performances have been given in the dark I-V rectifying curve and I-V working curve under illumination when exposed to AM 1.5 illumination condition (100 mW/cm/sup 2/, 25/spl deg/C). The open circuit voltage (V/sub oc/) and short circuit current density (J/sub sc/) for p-C:B/n-Si are observed to vary from 230 to 250 mV. The p-C:B/n-Si cell fabricated using the target with the amount of B by 3 weight percentages (Bwt%) shows highest energy conversion efficiency, /spl eta/=0.20% and fill factor, FF=45%. The quantum efficiency (QE) of the p-C:B/n-Si cells are observed to improve with Bwt%.

The characterization of carbon nitride alloy thin films deposited by pulsed laser deposition

Carbon nitride (CN x ) alloy thin films were deposited by pulsed laser deposition (PLD) with varying nitrogen gas pressure (NP) from 0.1 to 800 mTorr at 20°C of substrate temperature (ST) and with varying ST from 20 to 500°C at 0.8 Torr of NP. The effects of the NP and ST on the composition, structural and electrical properties of the nitrogen (N) incorporated camphoric carbon (CC) films have been investigated by standard measurement techniques. We found that, the amorphous structure of CN x films can be changed by NP and ST, and the CN x films with high N content have relatively high electrical resistivity.