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The effect of boron weight percentage in the camphoric carbon target of pulsed laser deposition on the preparation of boron-doped amorphous carbon (a-C:B) films has been studied using standard measurement techniques. XPS results showed the a-C:B films bonding properties almost unchanged at lower Bwt% up to 10 Bwt%, after which it changes with the increase of Bwt%, indicating increasing doping concentration with increase of Bwt% in the target. This phenomenon is further supported by FTIR and Visible-Raman spectroscopy analyses. The variation of bonding and structural properties are also correlated with the optical gap (E_g) and electrical resistivity (ρ) characteristics which are related to successful doping of B for low content of B in the amorphous carbon (a-C) films as the bonding, structural and E_g remain almost unchanged, and the ρ decreased untill the film deposited at 10 Bwt%. Since both the E_g and ρ decrease sharply with higher Bwt%, this phenomenon can be related to the graphitization.

The successful deposition of boron (B)-doped p-type (p-C:B) and phosphorous (P)-doped n-type (n-C:P) carbon (C) films, and fabrication of p-C:B on silicon (Si) substrate (p-C:B/n-Si) and n-C:P/p-Si cells by the technique of pulsed laser deposition (PLD) using graphite target is reported. The cells' performances are represented in the dark I–V rectifying curve and I–V working curve under illumination when exposed to AM 1.5 illumination condition (100 mW/cm², 25°C). The open circuit voltage (V_oc) and short circuit current density (J_sc) for p-C:B/n-Si are observed to vary from 230–250 mV and 1.5–2.2 mA/cm², respectively, and to vary from 215–265 mV and 7.5–10.5 mA/cm², respectively, for n-C:P/p-Si cells. The p-C:B/n-Si cell fabricated using the target with the amount of B by 3 Bwt% shows highest energy conversion efficiency, η = 0.20%, and fill factor, FF = 45%, while, the n-C:P/p-Si cell with the amount of P by 7 Pwt% shows highest energy conversion efficiency, η = 1.14%, and fill factor, FF = 41%. The quantum efficiencies (QE) of the p-C:B/n-Si and n-C:P/p-Si cells are observed to improve with Bwt% and Pwt%, respectively. The contributions of QE are suggested to be due to photon absorption by carbon layer in the lower wavelength region (below 750 nm) and Si substrates in the higher wavelength region. The dependence of B and P content on the electrical and optical properties of the deposited films, and the photovoltaic characteristics of the respective p-C:B/n-Si and n-C:P/p-Si heterojunction photovoltaic cells, are discussed.

This paper reports on the successful deposition of boron (B)-doped p-type (p-C:B) and phosphorus (P)-doped n-type (p-C:P) carbon (C) films, and the fabrication of p-C:B on silicon (Si) substrate (p-C:B/n-Si) and n-C:P/p-Si cells by a pulsed laser deposition (PLD) technique using a graphite target at room temperature. The boron and phosphorus atoms incorporated in the films were determined by X-ray photoelectron spectroscopy (XPS) to be in the range of 0.2–1.75 and 0.22–1.77 atomic percentages, respectively. 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 conditions (100 mW/cm², 25°C). The open circuit voltage (V_oc) and short circuit current density (J_sc) for p-C:B/n-Si are observed to vary from 230 to 250 mV and from 1.5 to 2.2 mA/cm², respectively; they vary from 215 to 265 mV and from 7.5 to 10.5 mA/cm², respectively, for n-C:P/p-Si cells. The p-C:B/n-Si cell fabricated using the target with the amount of boron by 3 weight percentages (Bwt%) showed the highest energy conversion efficiency, η = 0.20% and fill factor, FF = 45%. The n-C:P/p-Si cell fabricated using the target with the amount of 7 Pwt% showed the highest η = 1.14% and FF = 41%. The quantum efficiency (QE) of the p-C:B/n-Si and n-C:P/p-Si cells were observed to improve with Bwt% and Pwt%, respectively. The contribution of QE in the lower wavelength region (below 750 nm) may be due to photon absorption by the carbon layer, in the higher wavelength region it was due to the Si substrates. In this paper, the dependence of the boron and phosphorus content on the electrical and optical properties of the deposited films and the photovoltaic characteristics of the respective p-C:B/n-Si and n-C:P/p-Si heterojunction solar cells are discussed.

Segregation of boron on surface has been studied using the periodical calculations within the local density approximation. The obtained segregation energy (enthalpy) of about -1.9 eV is close to the published data of experimental studies and previous cluster semiempirical calculations. The influence of plane-wave basis set cutoff energy and the slab unit cell depth on the value of segregation energy has been investigated.

The aim of the present work is to determine the influence of technologically produced boron surface layers on the friction parameters in the sliding pairs under the conditions of mixed friction. The tribological evaluation included ion nitrided, pack borided, laser borided, quenched and tempered surface layers and TiB₂ coating deposited on 38CrAlMo_5-10, 46Cr₂ and 30MnB₄ steels. Modified surface layers of annular samples were matched under test conditions with counter-sample made from AlSn₂₀ bearing alloy. Tested sliding pairs were lubricated with 15 W/40 Lotos mineral engine oil. The tribological tests were conducted on a T-05 block on ring tester. The applied steel surface layer modification with boron allows surface layers to be created with pre-determined tribological characteristics required for the elements of kinematic pairs operating in the conditions of sliding friction. Pack boronizing reduces the friction coefficient during the start-up of the frictional pair and the maximum start-up resistance level is similar to the levels of pairs with nitrided surface layers.

The mechanism of boron-enhanced diffusion from a thin boron layer deposited on the surface in the case of silicon crystal doping is proposed and investigated. It was supposed that lattice contraction occurs in the vicinity of the surface due to the difference between the atomic radii of boron and silicon. This lattice contraction provides a stress-mediated diffusion of silicon self-interstitials from the near-surface region to the bulk of a semiconductor. Due to the stress-mediated diffusion, the near-surface region is depleted of silicon self-interstitials, and simultaneous oversaturation of this species occurs in the bulk. In this way, a strong nonuniform distribution of silicon self-interstitials in the vicinity of the surface is formed without regard to the large migration length of this species. The oversaturation of the bulk of a semiconductor with nonequilibrium self-interstitials allows one to explain the boron-enhanced diffusion of impurity atoms. The strong nonuniform distribution of these point defects also results in a specific form of boron concentration profile in the vicinity of the surface. Good agreement of the calculated boron profile with the experimental data for the entire doped region was obtained within the limit of the proposed model.