Effect of anodic-oxide layer thickness on the performance of GaAs MOS solar cells

Native oxide layers on n-type GaAs have been grown by aqueous anodic oxidation technique using AGW electrolyte. The effect of thickness of the As2O3rich interfacial oxide layer having a resistivity ~ 10¹⁴Ω . cm on the performance of GaAs MOS solar cells has been investigated. An attempt has been made to optimize the oxide layer thickness for achieving optimum efficiency.     

An analysis of the collection mechanisms in inversion layer solar cells

The characteristics of the surface-inversion-layer solar cell are analysed. The mechanisms of surface collection of the minority carrier, bulk generation and diffusion to the surface and lateral transport along the inversion channel are considered separately. The analysis illustrates the importance of the net inversion charge Q_I, and its influence on the geometrical design of the cell.     

MOS solar cells with oxides deposited by sol-gel spin-coating techniques

The metal-oxide-semiconductor (MOS) solar cells with sol-gel derived silicon dioxides (SiO₂) deposited by spin coating are proposed in this study. The sol-gel derived SiO₂ layer is prepared at low temperature of 450°C. Such processes are simple and low-cost. These techniques are, therefore, useful for largescale and large-amount manufacturing in MOS solar cells. It is observed that the short-circuit current (I _sc) of 2.48 mA, the open-circuit voltage (V _os) of 0.44 V, the fill factor (FF) of 0.46 and the conversion efficiency (η%) of 2.01% were obtained by means of the current-voltage (I–V) measurements under AM 1.5 (100 mW/cm²) irradiance at 25°C in the MOS solar cell with sol-gel derived SiO₂.     

Computer analysis of the double-diffused MOS transistor for integrated circuits

The effective length of an MOS transistor can be made narrow by using double diffusion similar to a bipolar transistor. Computations were conducted for an n-channel double-diffused transistor with different surface concentrations, channel lengths, channel gradients, surface-states densities, and substrate concentrations. A shorter channel length and a higher surface-state density, e.g.langle1, 1, 1ranglecrystal, gave a higher drain current and transconductance. The maximum transconductance in many cases occurs at low gate voltages. The computations indicate that a gain-bandwidth product in the gigahertz range can be expected when the graded channel region is less than 1 µm. The difference between an n-type substrate and a p-type substrate is not substantial. The analysis is also useful in predicting the performance of any integrated logic circuit using the diffused enhancement transistor as the active switch and a depletion-mode transistor (without a diffused channel) as the load device. The computation indicates that satisfactory performance can be obtained using a load device with the same geometry and an ON voltage of only a fraction of a volt, This revelation indicates that double-diffused channel MOS transistors not only give higher speed but also smaller chip area for integrated circuits and a lower supply voltage (hence less power dissipation).     

Static-noise margin analysis of MOS SRAM cells

The stability of both resistor-load (R-load) and full-CMOS SRAM cells is investigated analytically as well as by simulation. Explicit analytic expressions for the static-noise margin (SNM) as a function of device parameters and supply voltage are derived. The expressions are useful in predicting the effect of parameter changes on the stability as well as in optimizing the design of SRAM cells. An easy-to-use SNM simulation method is presented, the results of which are in good agreement with the results predicted by the analytic SNM expressions. It is further concluded that full-CMOS cells are much more stable than R-local cells at a low supply voltage.     

Characteristics of MOS solar cells built on (n-type) InP substrates

An examination is made of the electrical and photovoltaic characteristics of Au- (n-type) InP Schottky-barrier solar cells with and without a thin anodic oxide layer at the interface. Cells built on anodized surface (MOS type) exhibit a reduction of dark current by three orders of magnitude and an increase in the barrier height (≃ 0.80 eV) by 0.30 eV, over conventional Schottky-barrier devices. Current transport in both type of cells is limited by thermionic emission of carriers and an increase in n factor from 1.02 to 1.16 is observed for MOS cells. Under illumination, MOS cells show an increase of open-circuit voltage to 0.46 V without any reduction in the short-circuit current which is obtained as 17.20 mA/cm². The efficiency has been found to go up from 3.45 to 6 percent for MOS cells which show an excellent spectral response, almost flat over a large portion of the visible spectrum.     

17.3% efficiency metal-oxide-semiconductor (MOS) solar cells withliquid-phase-deposited silicon dioxide

Simple and high efficiency silicon metal-oxide semiconductor (MOS) solar cells, with silicon dioxide prepared by a room-temperature liquid phase deposition (LPD) method, are proposed. The thickness of LPD oxide is about 5 nm. After adding a 2~5 nm semi-transparent thin Al film between the 200 nm patterned Al cathode, all the solar cells' performance parameters are improved. For a cell exposed under 15 mW/cm ², short-circuit current density J_SC up to 10.7 mA/cm², open-circuit voltage V_OC up to 412 mV, fill factor FF up to 59, and record effective conversion efficiency η up to 17.3% are obtained for this structure. Photo-conductivity properties of LPD oxide are found and the mechanism is discussed     

Epitaxial silicon solar cells with uniformly doped layer

Solar cell structures have been prepared both by successive deposition of p-type and n-type silicon layers on p⁺-type single-crystal silicon. Impurities are uniformly doped at epitaxial layers. Efficiency of 9.0 percent with the epitaxial layer junction structure and 12.8 percent with the diffused 0.3-μm junction depth structure have been achieved.     

基于InGaAs渐变缓冲层的太阳能电池的研究

This paper uses an InGaAs graded buffer layer to solve the problem of lattice mismatch and device performance degradation. In the graded buffer layer, we choose the ＂transition layer＂ and the ＂cover layer＂ to accommodate the 3.9% mismatch. No threading dislocations were observed in the uppermost part of the epitaxial layer stack when using a transmission electron microscope （TEM）. We analyze the factors which influence the saturation current. Simulation data shows that the cells grown by metal organic vapor phase epitaxy （MOVPE） have considerable open circuit voltage, short circuit current, and photoelectric conversion efficiency. Finally we propose that InP may have great development potential as a substrate material.     

Emitter layer optimization in heterojunction bifacial silicon solar cells

Silicon solar cells continue to dominate the market, due to the abundance of silicon and their acceptable efficiency. The heterojunction with intrinsic thin layer (HIT) structure is now the dominant technology. Increasing the efficiency of these cells could expand the development choices for HIT solar cells. We presented a detailed investigation of the emitter a-Si:H(n) layer of a p-type bifacial HIT solar cell in terms of characteristic parameters which include layer doping concentration, thickness, band gap width, electron affinity, hole mobility, and so on. Solar cell composition: (ZnO/nc-Si:H(n)/a-Si:H(i)/c-Si(p)/a-Si:H(i)/nc-Si:H(p)/ZnO). The results reveal optimal values for the investigated parameters, for which the highest computed efficiency is 26.45% when lighted from the top only and 21.21% when illuminated from the back only.     

Perovskite solar cells with NiOx hole-transport layer

<正>Inverted perovskite solar cells(PSCs) have attracted interest due to their simple fabrication, long-term stability, and small hysteresis^[1-3]. It is noteworthy that the quality of the hole-transport layer(HTL) largely determines the device performance. Nickel oxide(NiO_x) has been paid great attention as a hole-transport material in PSCs because of its natural p-type property, low cost, good stability, and high transmittance^{[4, 5]}.     

Computer aided analysis and design of MOS translinear circuits operating in strong inversion

Recently, it was proposed to generalize the well-known translinear circuit principle in such a way that it also applies to MOS transistors operated in strong inversion. In this paper, the MOS translinear (MTL) principle will be briefly reviewed. A graphical analysis method for MTL-circuits is presented, which can also be applied to bipolar translinear circuits. This graphical method was implemented in a computer program, which is now used as an interactive design tool to implement nonlinear signal processing functions by MTL circuits.     

Computer simulation of amorphous silicon based alloy p-i-n solar cells

We report on the results of a computer simulation of amorphous silicon-based alloy p-i-n solar cells based on the complete set of transport equations. Our model takes into account the spatial and energy variations of the localized state spectrum, nonuniform doping profiles, and nonuniform optical excitation. The computed dark and light current-voltage characteristics are in good agreement with experimental data. Our results suggest that carrier back diffusion is not a significant effect in optimized p-in devices and that the open circuit voltage is determined by the recombination current. We also show the importance of residual boron doping in the intrinsic layer for cells illuminated through the n+ layer, and that hole transport limits device performance.     

Polymer solar cells based on inkjet-printed PEDOT:PSS layer

In this article, we have demonstrated solar cell performance of the inkjet-printed PEDOT:PSS layer and the roles of additives in device efficiency. The newly proposed PEDOT:PSS inks with additives of glycerol and surfactant show the improved surface morphology and high conductivity resulting in the enhanced photovoltaic performance. Using the optimized ink formulation of PEDOT:PSS, we have demonstrated a 3.16% efficient solar cell with an inkjet printing.     

Room temperature solution-processed electron transport layer for organic solar cells

We present a new recipe for a solution-processed titanium oxide (TiO_x) based electron transport layer at room temperature. Due to its high chemical compatibility with all types of organic blends (semi-crystalline or amorphous) and it is good adhesion to both surfaces of glass/ITO substrate and the active layer (blend), the buffer layer is suitable for use in organic solar cell devices with conventional, inverted or multi-junction structures. The main goal of this recipe is producing with easiness an repeatable and stable precursor that will leads to titanium oxide buffer layer each time with the same quality. Since the processing of the titanium oxide layer itself does not require any initial or additional treatment before and after the coating, and can even be carried in air as well as under protective atmosphere, our room temperature solution-processed electron transport layer is highly versatile and very promising for cost effective mass production of organic solar cells.     

Double layer antireflection coating for high-efficiency passivatedemitter silicon solar cells

Recent high-efficiency silicon solar cells employ high-quality oxides both for surface passivation and as a rudimentary antireflection coating. This gives over 3% reflection at the cell front surface, even though the surface is microstructured. A double layer antireflection coating applied to cells with reduced SiO₂ thickness reduces the cell reflection. However, although reflection is minimized by reducing the oxide thickness to values below 100 Å, a rapid falloff in both open-circuit voltage and short-circuit current is observed experimentally once this thickness is reduced below 200 Å. The best compromise is found when oxide thickness is 250 Å which allows improved short-circuit current density without appreciable loss in open-circuit voltage     

Highly conductive Zinc-Tin-Oxide buffer layer for inverted polymer solar cells

Thin-films of Zinc Tin Oxide (ZTO) with an extremely high charge carrier mobility and superior optical transmittance are synthesized using a simple solution method. These ZTO films have been systematically studied for the application in inverted polymer solar cells (PSCs). The Hall effects measurements show that the charge mobility of the ZTO semiconductor is over 16.5 cm².V⁻¹.S⁻¹, which is the highest mobility value ever reported for oxide buffer made by using solution process. By applying the ZTO buffer layer in the inverted PSCs of P3HT:PC₆₁BM, the power conversion efficiency of the device is 30% higher than that of the devices made with other common buffer layers such as ZnO and TiO₂. Light intensity-dependent JV studies and PL measurements also indicate that ZTO buffer layer reduces surface recombination. This work demonstrates that the solution-synthesized ZTO is a promising new buffer layer with superior electron extraction capability for the solar cells.     

窗口层对三结电池双层减反膜的影响

窗口层的厚度对高效三层太阳能电池具有重要影响。本文针对太阳能电池的地面应用,优化了三节电池（Ga0.5In0.5P/In0.02Ga0.98As/Ge）的双层反射膜（SiO2/TiO2, SiO2/ZnS）。同时讨论了在双层减反膜优化结构下,变化Al0.5In0.5P窗口层厚度引起反射率的变化。     

Influence of window layer thickness on double layer antireflection coating for triple junction solar cells

The optimization of a SiO₂/TiO₂,SiO₂/ZnS double layer antireflection coating（ARC）on Ga_0.5In_0.5P/In_0.02Ga_0.98As/Ge solar cells for terrestrial application is discussed.The Al_0.5In_0.5P window layer thickness is also taken into consideration.It is shown that the optimal parameters of double layer ARC vary with the thickness of the window layer.     

Effects of nonuniformity of the insulating layer on MIS solar cells

Recently, MIS solar cells have received much attention, because of their enhanced photovoltaic response compared to the MS solar cells. Some theories have been reported which deal with the effects of the insulating layer on the performance of the solar devices. However, it has been established that the silicon/silicon dioxide interface is rough, and therefore, the insulating layer cannot be expected to be uniform. Deviation from perfect interfaces may result in a large change in the electrical characteristics of the solar devices. A computation is presented which shows this effect can be significant and may make identification of other effects difficult.