• Korean Journal of Materials Research
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• v.10 no.7
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• pp.478-481
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• 2000

Single phase $Pb(Mg_{1/3}Nb_{2/3})O_3$ ceramics doped by 10 mol% of electron donors such as $La^3,\; Pr^{3+,4+},\; Nd^{3+},\; Sm^{3+}$, were synthesized and their B-site cationic ordering structures were investigated by XRD and TEM. In the XRD patterns, only fundamental reflections were observed for the undoped $Pb(Mg_{1/3}Nb_{2/3})O_3$, while the (h/2 $\textsc{k}$/2ι/2)(h,$\textsc{k}$,ι all odd) superlattice reflections resulting from the 1:1 ordering induced unit cell doubling were also observed for the donor-doped $Pb(Mg_{1/3}Nb_{2/3})O_3$. In the TEM selected area diffraction patterns, the (h/2 k/2 l/2)(h,k,l all odd) superlattice reflection spots as well as the fundamental reflection spots were observed for all the samples, but the relative intensities of the superlattice reflection spots to the fundamental reflection spots were significantly enhanced by the donor-doping. In the TEM dark-field images, antiphase boundaries were observed only for the donor-doped $Pb(Mg_{1/3}Nb_{2/3})O_3$. It was therefore experimentally verified that doping by electron donors such as $La^3,\; Pr^{3+,4+},\; Nd^{3+},\; Sm^{3+}$, enhances the B-site cationic 1:1 ordering in $Pb(Mg_{1/3}Nb_{2/3})O_3$. These experimental results were interpreted in terms of the charge compensation mechanism.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.297-297
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• 2010

Precise control of the position and density of doping elements at the nanoscale is becoming a central issue for realizing state-of-the-art silicon-based optoelectronic devices. As dimensions are scaled down to take benefits from the quantum confinement effect, however, the presence of interfaces and the nature of materials adjacent to silicon turn out to be important and govern the physical properties. Utilization of visible light is a promising method to overcome the efficiency limit of the crystalline Si solar cells. Si quantum dots (QDs) have been proposed as an emission source of visible light, which is based on the quantum confinement effect. Light emission in the visible wavelength has been reported by controlling the size and density of Si QDs embedded within various types of insulating matrix. For the realization of all-Si QD solar cells with homojunctions, it is prerequisite not only to optimize the impurity doping for both p- and n-type Si QDs, but also to construct p-n homojunctions between them. In this study, XPS and SIMS were used for the development of p-type and n-type Si quantum dot solar cells. The stoichiometry of SiOx layers were controlled by in-situ XPS analysis and the concentration of B and P by SIMS for the activated doping in Si nano structures. Especially, it has been experimentally evidenced that boron atoms in silicon nanostructures confined in SiO2 matrix can segregate into the Si/$SiO_2$ interfaces and the Si bulk forming a distinct bimodal spatial distribution. By performing quantitative analysis and theoretical modelling, it has been found that boron incorporated into the four-fold Si crystal lattice can have electrical activity. Based on these findings, p-type Si quantum dot solar cell with the energy-conversion efficiency of 10.2% was realized from a [B-doped $SiO_{1.2}$(2 nm)/$SiO_2(2\;nm)]^{25}$ superlattice film with a B doping level of $4.0{\times}10^{20}\;atoms/cm^2$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.456-456
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• 2009

Boron doping on an n-type Si wafer is requisite process for IBC (Interdigitated Back Contact) solar cells. Fiber laser annealing is one of boron doping methods. For the boron doping, uniformly coated or deposited film is highly required. Plasma enhanced chemical vapor deposition (PECVD) method provides a uniform dopant film or layer which can facilitate doping. Because amorphous silicon layer absorption range for the wavelength of fiber laser does not match well for the direct annealing. In this study, to enhance thermal affection on the existing p-a-Si:H layer, a ${\mu}c$-Si:H intrinsic layer was deposited on the p-a-Si:H layer additionally by PECVD. To improve heat transfer rate to the amorphous silicon layer, and as heating both sides and protecting boron eliminating from the amorphous silicon layer. For p-a-Si:H layer with the ratio of $SiH_4$ : $B_2H_6$ : $H_2$ = 30 : 30 : 120, at $200^{\circ}C$, 50 W, 0.2 Torr for 30 minutes, and for ${\mu}c$-Si:H intrinsic layer, $SiH_4$ : $H_2$ = 10 : 300, at $200^{\circ}C$, 30 W, 0.5 Torr for 60 minutes, 2 cm $\times$ 2 cm size wafers were used. In consequence of comparing the results of lifetime measurement and sheet resistance relation, the laser condition set of 20 ~ 27 % of power, 150 ~ 160 kHz, 20 ~ 50 mm/s of marking speed, and $10\;{\sim}\;50 {\mu}m$ spacing with continuous wave mode of scanner lens showed the correlation between lifetime and sheet resistance as $100\;{\Omega}/sq$ and $11.8\;{\mu}s$ vs. $17\;{\Omega}/sq$ and $8.2\;{\mu}s$. Comparing to the singly deposited p-a-Si:H layer case, the additional ${\mu}c$-Si:H layer for doping resulted in no trade-offs, but showed slight improvement of both lifetime and sheet resistance, however sheet resistance might be confined by the additional intrinsic layer. This might come from the ineffective crystallization of amorphous silicon layer. For the additional layer case, lifetime and sheet resistance were measured as $84.8\;{\Omega}/sq$ and $11.09\;{\mu}s$ vs. $79.8\;{\Omega}/sq$ and $11.93\;{\mu}s$. The co-existence of $n^+$layeronthesamesurfaceandeliminating the laser damage should be taken into account for an IBC solar cell structure. Heavily doped uniform boron layer by fiber laser brings not only basic and essential conditions for the beginning step of IBC solar cell fabrication processes, but also the controllable doping concentration and depth that can be established according to the deposition conditions of layers.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.4
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• pp.285-296
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• 2005

Reduced pressure chemical vapor deposition technology has been used to study SiGe heterostructure epitaxy and device issues, including SiGe relaxed buffers, proper control of Ge component and crystalline defects, two dimensional delta doping, and their influence on electrical properties of devices. From experiments, 2D profiles of B and P presented FWHM of 5 nm and 20 nm, respectively, and doses in 5×10/sup 11/ ∼ 3×10/sup 14/ ㎝/sup -2/ range. The results could be employed to fabricate SiGe/Si heterostructure field effect transistors with both Schottky contact and MOS structure for gate electrodes. I-V characteristics of 2D P-doped HFETs revealed normal behavior except the detrimental effect of crystalline defects created at SiGe/Si interfaces due to stress relaxation. On the contrary, sharp B-doping technology resulted in significant improvement in DC performance by 20-30 ％ in transconductance and short channel effect of SiGe HMOS. High peak concentration and mobility in 2D-doped SiGe heterostructures accompanied by remarkable improvements of electrical property illustrate feasible use for nano-sale FETs and integrated circuits for radio frequency wireless communication in particular.

• Journal of the Korean Vacuum Society
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• v.9 no.2
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• pp.110-115
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• 2000

Deposition conditions of diamond thin films were optimized using hot-filament chemical vapor deposition (HFCVD). Boron-doped diamond thin films with varying boron densities were then fabricated using B4C solid pellets. Current-voltage responses and field emission currents were measured to test the characteristics of field emission display (FED). With the increase of boron doping, the crystal size of diamond decreased slightly, but its quality was not changed significantly in case of small doping. The I-V characterization was performed for Al/diamond/p-Si, and the current of doped diamond film was increased $10^4\sim10^5$ times as compared with that of undoped film. In the field emission properties, the electrons were emitted with low electric field with the increase of doping, while the emission current increased. The onset-field of electron emission was 15.5 V/$\mu\textrm{m}$ for 2 pellets, 13.6 V/$\mu\textrm{m}$ for 3 pellets and 11.1 V/$\mu\textrm{m}$ for 4 pellets. With the incorporation of boron, the slope of Fowler-Nordheim graph was decreased, revealing that the electron emission behavior was improved with the decrease of the effective barrier energy.

• Journal of Sensor Science and Technology
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• v.5 no.1
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• pp.63-70
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• 1996

Silicon epitaxial films of submicron level were successfully grown by the RTCVD method. For the growth of silicon epitaxial layers, $SiH_{2}Cl_{2}\;/\;H_{2}$ gas mixtures and various process parameters including $H_{2}$ prebake process were used. The growth conditions were varied to investigate their effects on the interface abruptness of doping profile, the film growth rates and crystalline properties. The crystallinity of the undoped silicon was excellent at the growth temperature of $900^{\circ}C$. The doping profiles were measured by SIMS technique. The abruptness of doping profile would be controlled within about $200{\AA}/decade$ in the structure of undoped Si / $n^{+}-Si$ substrate.

• Korean Chemical Engineering Research
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• v.55 no.6
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• pp.861-867
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• 2017

In order to improve the capacity and cycling stability of Ni-rich NCA cathode materials for lithium ion batteries, the boron and cobalt were doped in commercial $Li_{1.06}Ni_{0.91}Co_{0.08}Al_{0.01}O_2$ (NCA) powders. Commercial NCA particles are mixed composites such as secondary particles of about $5{\mu}m$ and $12{\mu}m$, and the particle size was decreased by doping boron and cobalt. The initial discharge capacities of the boron and cobalt doped NCA-B and NCA-Co were found to be 214 mAh/g and 200 mAh/g, respectively, which are higher values than that of the raw NCA cathode material. In particular, NCA-Co exhibits the best discharge capacity of 157 mAh/g after 20 cycles, which is probably due to the enhanced diffusion of lithium ion by crystal growth along with the c-axis direction.

• Korean Journal of Materials Research
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• v.29 no.3
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• pp.150-154
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• 2019

This study investigates the effect of MnO2 and CuO as acceptor additives on the microstructure and piezoelectric properties of $0.96(K_{0.5}Na_{0.5})_{0.95}Li_{0.05}Nb_{0.93}Sb_{0.07}O_3-0.04BaZrO_3$, which has a rhombohedral-tetragonal phase boundary composition. $MnO_2$ and CuO-added $0.96(K_{0.5}Na_{0.5})_{0.95}Li_{0.05}Nb_{0.93}Sb_{0.07}O_3-0.04BaZrO_3$ ceramics sintered at a relatively low temperature of $1020^{\circ}C$ show a pure perovskite phase with no secondary phase. As the addition of $MnO_2$ and CuO increases, the sintered density and grain size of the resulting ceramics increases. Due to the difference in the amount of oxygen vacancies produced by B-site substitution, Cu ion doping is more effective for uniform grain growth than Mn ion doping. The formation of oxygen vacancies due to B-site substitution of Cu or Mn ions results in a hardening effect via ferroelectric domain pinning, leading to a reduction in the piezoelectric charge coefficient and improvement of the mechanical quality factor. For the same amount of additive, the addition of CuO is more advantageous for obtaining a high mechanical quality factor than the addition of $MnO_2$.

• Proceedings of the Korean Magnestics Society Conference
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• 2007.05a
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• pp.193.1-193.1
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• 2007

• 한국초전도학회:학술대회논문집
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• 2009.07a
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• pp.50-50
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• 2009