零偏退火与反偏退火对含氢的Au／n—Si肖特基势垒的控制

＜１１１＞晶向的掺磷的ｎ型硅外延片经等离子进氢后连同未经等离子氢处理的对比片一起淀积金，制得Ａｕ／ｎ－Ｓｉ肖特基势垒，实验结果表明：氢能使Ａｕ／ｎ－Ｓｉ的肖特基势垒高度下降０．１３ｅＶ；含氢的肖特基势垒的高度可以被零偏退火与反偏退火所控制，即零偏退火使含氢的肖特基势垒的高度降低，而反偏退火使含氢的肖特基势垒的高度升高；而且零偏退火与反偏退火对肖特基势垒高的这种控制作用至少在三个循环过程中是可逆的。     

零偏退火与反偏退火对含氢的Au/n-Si肖特基势垒的控制

〈１１１〉晶向的掺磷的ｎ型硅外延片经等离子进氢后连同未经等离子氢处理的对比片一起淀积金，制得Ａｕ／ｎ－Ｓｉ肖特基势垒。实验结果表明：氢能使Ａｕ／ｎ－Ｓｉ的肖特基势垒高度下降０．１３ｅＶ；含氢的肖特基势垒的高度可以被零偏退火与反偏退火所控制，即零偏退火使含氢的肖特基势垒的高度降低，而反偏退火使含氢的肖特基势垒的高度升高；而且零偏退火与反偏退火对肖特基势垒高的这种控制作用至少在三个循环过程中是可逆的。在反偏退火以后，含氢的肖特基势垒的高度升高的数值不仅与退火时所应用的偏置电压有关，而且与退火温度也有关。     

Effect of graphene tunnel barrier on Schottky barrier height of Heusler alloy Co_2MnSi/graphene/n-Ge junction

We demonstrate that the insertion of a graphene tunnel barrier between Heusler alloy Co_2MnSi and the germanium(Ge) channel modulates the Schottky barrier height and the resistance–area product of the spin diode. We confirm that the Fermi level is depinned and a reduction in the electron Schottky barrier height(SBH) occurs following the insertion of the graphene layer between Co_2MnSi and Ge. The electron SBH is modulated in the 0.34 eV–0.61 eV range. Furthermore,the transport mechanism changes from rectifying to symmetric tunneling following the insertion. This behavior provides a pathway for highly efficient spin injection from a Heusler alloy into a Ge channel with high electron and hole mobility.     

RF-PECVD掺溴非晶碳氢膜的Raman光谱分析

在室温条件下,以溴乙烷为单体、氢气为载气,用13.56 MHz射频等离子体化学气相淀积方法(RF-PECVD)在硅片衬底上生长了掺溴非晶碳氢薄膜(a-C:Br:H).通过对其进行Raman光谱分析,研究了工作气压对薄膜结构的影响.结果显示:随着气体工作压力从20 Pa下降至5 Pa,样品D峰强度增强,I_D/I_G值逐步由1.18增加至1.36,G峰的位置向高频轻微移动;与此同时,薄膜生长方式逐步转为低能态形式生长,薄膜中sp~2C逐步由链式结构向环式结构转化.     

Mode-Locked Erbium-Doped Fiber Laser Using Vanadium Oxide as Saturable Absorber

A mode-locked erbium doped fiber laser(EDFL) is demonstrated using the vanadium oxide(V_2O_5) material as a saturable absorber(SA). The V_2O_5 based SA is hosted into poly ethylene oxide film and attached on fiber ferule in the laser cavity. It shows 7% modulation depth with 71 MW/cm~2 saturation intensity. By incorporating the SA inside the EDFL cavity with managed intra-cavity dispersion, ultrashort soliton pulses are successfully generated with a full width at half maximum of 3.14 ps. The laser operated at central wavelength of 1559.25 nm and repetition frequency of 1 MHz.     

Single-electron tunneling in silicon nanostructures

We present a brief overview on different realizations of single-electron devices fabricated in silicon-on-insulator films. Lateral structuring of highly doped silicon films allows us to observe quasi-metallic Coulomb blockade oscillations in shrunken wires where no quantum dot structure is geometrically defined. Embedding quantum dot structures into the inversion channel of a silicon-on-insulator field-effect transistor Coulomb blockade up to 300 K is observed. In contrast to the quasi-metallic structures, in these devices the influence of the quantum mechanical level spacing inside the dot becomes visible. Suspending highly doped silicon nanostructures leads to a novel kind of Coulomb blockade devices allowing both high-power application as well as the study of electron–phonon interaction. Received: 14 April 2000 / Accepted: 17 April 2000 / Published online: 6 September 2000     

快速热退火对Co/Si0.85Geo.15肖特基结电学特性的影响

用离子束溅射技术分别在SiO2和单晶Si衬底上沉积了Si1-xGex和Co薄膜.在不同温度下,对Co/Si1-xGex肖特基结进行快速热退火处理(RTA),对处理后的样品进行了表面形貌和电学测量.发现退火温度升高,样品表面粗糙度变大,理想因子也变大,但对肖特基势垒高度(SBH)的影响很小.分析认为,随着退火温度的升高,...     

基于LNDM模型的碳离子束混合辐射场相同剂量平均LET下关键纳剂量学指标及RBE分析

纳剂量学量正在成为新的表征辐射品质的量,也是用于精确计算相对生物学效应(RBE)的基础数据.具有相同剂量平均传能线密度(LET)离子束混合辐射场导致的生物学效应也未必相同.为研究关键纳剂量学指标[电离簇尺寸NICS≥1的条件概率密度分布的一阶矩(M C11)、NICS≥2的条件概率密度分布的一阶矩(M C21)、NIC...     

Performance assessment of nanoscale Schottky MOSFET as resonant tunnelling device: Non-equilibrium Green’s function formalism

A comprehensive study is performed on the electrical characteristics of Schottky barrier MOSFET (SBMOSFET) in nanoscale regime, by employing the non-equilibrium Green’s function (NEGF) approach. Quantum confinement results in the enhancement of effective Schottky barrier height (SBH). High enough Schottky barriers at the source/drain and the channel form a double barrier profile along the channel that results in the formation of resonance states. We have, for the first time, proposed a resonant tunnelling device based on SBMOSFET in which multiple resonance states are modulated by the gate voltage. Role of essential factors such as temperature, SBH, bias voltage and structural parameters on the feasibility of this device for silicon-based resonant tunnelling applications are extensively studied. Resonant tunnelling appears at low temperatures and low drain voltages and as a result negative differential resistance (NDR) is apparent in the transfer characteristic. Scaling down the gate length to 6 nm increases the peak-to-valley ratio (PVR) of the drain current. As the effective SBH reduces, the curvature of the double barrier profile is gradually diminished. Therefore, multiple resonant states are contributed to the current and consequently resonant tunnelling is smoothed out.     

C60分子与石墨(0001)、硅(111)面的碰撞

用分子动力学模拟的方法和Tersoff多体势函数对以一定能量入射的C 60在石墨(0001)表面以及硅(111)表面碰撞的过程进行模拟研究.结果发现:碰撞过程是高度非弹性的,在弹回过程中,C60分子质心的运动可被看作是在准谐势下的运动 .C60以240 eV初始能量入射到石墨表面时,C60分子有严重的扭曲,最终将平铺在石墨表面形成薄膜;C60分子以30 eV初始动能入射到石墨表面时,将保持完好球形沉积在石墨表面;C60分子以60 eV的初始动能碰撞硅(111)表面时,C60分子最终沉积在硅表面,碰撞过程中C60分子有形变.     

Experimental test of the high-frequency quantum shot noise theory in a quantum point contact

We report on direct measurements of the electronic shot noise of a quantum point contact at frequencies nu in the range 4-8 GHz. The very small energy scale used ensures energy independent transmissions of the few transmitted electronic modes and their accurate knowledge. Both the thermal energy and the quantum point contact drain-source voltage V_{ds} are comparable to the photon energy hnu leading to observation of the shot noise suppression when V_{ds}相似文献   

Observation of hopping transitions for delocalized electrons by temperature-dependent conductance in silicon junctionless nanowire transistors

We demonstrate transitions of hopping behaviors for delocalized electrons through the discrete dopant-induced quantum dots in n-doped silicon junctionless nanowire transistors by the temperature-dependent conductance characteristics.There are two obvious transition platforms within the critical temperature regimes for the experimental conductance data,which are extracted from the unified transfer characteristics for different temperatures at the gate voltage positions of the initial transconductance gm peak in V_(g1) and valley in V_(g2). The crossover temperatures of the electron hopping behaviors are analytically determined by the temperature-dependent conductance at the gate voltages V_(g1) and V_(g2). This finding provides essential evidence for the hopping electron behaviors under the influence of thermal activation and long-range Coulomb interaction.     

A super-junction SOI-LDMOS with low resistance electron channel

A novel super-junction LDMOS with low resistance channel(LRC), named LRC-LDMOS based on the silicon-oninsulator(SOI) technology is proposed. The LRC is highly doped on the surface of the drift region, which can significantly reduce the specific on resistance(Ron,sp) in forward conduction. The charge compensation between the LRC, N-pillar,and P-pillar of the super-junction are adjusted to satisfy the charge balance, which can completely deplete the whole drift,thus the breakdown voltage(BV) is enhanced in reverse blocking. The three-dimensional(3 D) simulation results show that the BV and R_(on,sp) of the device can reach 253 V and 15.5 mΩ·cm~2, respectively, and the Baliga's figure of merit(FOM = BV~2/R_(on,sp)) of 4.1 MW/cm~2 is achieved, breaking through the silicon limit.     

CMOS—compatible reconfigurable microring demultiplexer with doped silicon slab heater

We present a 1×4 reconfigurable demultiplexer based on cascaded silicon microring resonators. The device is fabricated on a 0.18 μm complementary metal oxide semiconductor (CMOS) process. A homogeneous doped silicon slab heater is proposed and fabricated directly on the slab region of the microring resonator for thermal tuning. The flows of the heating currents in the heaters are parallel to the ring waveguide through the heavily doped slab regions located on both sides of the ring waveguide without through the waveguide core regions. The proposed doped heaters are experimentally verified with low-voltage operation and tuning efficiency of ～77 pm/mW. Without any tuning or trimming, predicted average channel spacing distribution in the whole free spectral range (FSR) is demonstrated. Full reconfigurability is also demonstrated in the demultiplexer with channel spacing of 2 nm (250 GHz) and 1 nm (125 GHz), corresponding to channel isolation of less than ?21 dB and ?16 dB, respectively. Such a low-voltage operation and reconfigurable demultiplexer is suitable for on-chip optical interconnect.     

Surface passivation schemes for high‐efficiency n‐type Si solar cells

An effective passivation on the front side boron emitter is essential to utilize the full potential of solar cells fabricated on n‐type silicon. However, recent investigations have shown that it is more difficult to achieve a low surface recombination velocity on highly doped p‐type silicon than on n‐type silicon. Thus, the approach presented in this paper is to overcompensate the surface of the deep boron emitter locally by a shallow phosphorus diffusion. This inversion from p‐type to n‐type surface allows the use of standard technologies which are used for passivation of highly doped n‐type surfaces. Emitter saturation current densities (J_0e) of 49 fA/cm² have been reached with this approach on SiO₂ passivated lifetime samples. On solar cells a certified conversion efficiency of 21.7% with an open‐circuit voltage (V_oc) of 676 mV was achieved. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Electrolytic hydrogenation of p-type silicon bulk and surface modifications

An electrolytic method is used to introduce hydrogen into p-type silicon, at room temperature. The results of SIMS analysis indicate that hydrogen diffuses more rapidly in highly doped samples than in low doped samples, in contrast with the results of plasma annealing. The electrochemical technique creates a large number of surface defects, probably related to the existence of a thin hydrogenated layer beneath the surface.     

Low-voltage antimony-doped SnO₂ nanowire transparent transistors gated by microporous SiO₂-based proton conductors

A battery drivable low-voltage transparent lightly antimony(Sb)-doped SnO 2 nanowire electric-double-layer(EDL) field-effect transistor(FET) is fabricated on an ITO glass substrate at room temperature.An ultralow operation voltage of 1 V is obtained on account of an untralarge specific gate capacitance(～2.14 μF/cm 2) directly bound up with mobile ions-induced EDL(sandwiched between the top and bottom electrodes) effect.The transparent FET shows excellent electric characteristics with a field-effect mobility of 54.43 cm 2 /V · s,current on/off ration of 2 × 10 4,and subthreshold gate voltage swing(S = dV gs /d(log I ds)) of 140 mV/decade.The threshold voltage V th(0.1 V) is estimated which indicates that the SnO 2 namowire transistor operates in an n-type enhanced mode.Such a low-voltage transparent nanowire transistor gated by a microporous SiO 2-based solid electrolyte is very promising for battery-powered portable nanoscale sensors.     

High-power SiC MESFET using a dual p-buffer layer for an S-band power amplifier

A silicon carbide (SiC) based metal semiconductor field effect transistor (MESFET) is fabricated by using a standard SiC MESFET structure with the application of a dual p-buffer layer and a multi-recessed gate to the process for an S-band power amplifier. The lower doped upper-buffer layer serves to maintain the channel current, while the higher doped lower-buffer layer is used to provide excellent electron confinement in the channel layer. A 20-mm gate periphery SiC MESFET biased at a drain voltage of 85 V demonstrates a pulsed wave saturated output power of 94 W, a linear gain of 11.7 dB, and a maximum power added efficiency of 24.3% at 3.4 GHz. These results are improved compared with those of the conventional single p-buffer MESFET fabricated in this work using the same process. A radio-frequency power output greater than 4.7 W/mm is achieved, showing the potential as a high-voltage operation device for high-power solid-state amplifier applications.     

Physical Properties of C-Si Alloys in C2/m Structure

Using the first principles calculations based on density functional theory, the crystal structure, elastic anisotropy, and electronic properties of carbon, silicon and their alloys(C_(12)Si_4, C_8Si_8, and C_4Si_(12)) in a monoclinic structure(C2/m) are investigated. The calculated results such as lattice parameters, elastic constants, bulk modulus,and shear modulus of C_(16) and Si_(16) in C2/m structure are in good accord with previous work. The elastic constants show that C_(16), Si_(16), and their alloys in C2/m structure are mechanically stable. The calculated results of universal anisotropy index, compression and shear anisotropy percent factors indicate that C-Si alloys present elastic anisotropy,and C_8Si_8 shows a greater anisotropy. The Poisson's ratio and the B/G value show that C_8Si_8 is ductile material and other four C-Si alloys are brittle materials. In addition, Debye temperature and average sound velocity are predicted utilizing elastic modulus and density of C-Si alloys. The band structure and the partial density of states imply that C_(16) and Si_(16) are indirect band gap semiconductors, while C_(12)Si_4, C_8Si_8, and C_4Si_(12) are semi-metallic alloys.     

Micro‐photoluminescence spectroscopy on heavily‐doped layers of silicon solar cells

We report and explain the photoluminescence spectra emitted from silicon solar cells with heavily‐doped layers at the surface. A micro‐photoluminescence spectroscopy system is employed to investigate the total spectrum emitted from both the heavily‐doped layer and the silicon substrate with micron‐scale spatial resolution. The two regions of the device give rise to separate photoluminescence peaks, due to band‐gap narrowing effects in the highly‐doped layer. Two key parameters, the absorption depth of the excitation wavelength, and the sample temperature, are shown to be critical to reveal the separate signatures from the two regions. Finally, this technique is applied to locally diffused and laser‐doped regions on silicon solar cell pre‐cursors, demonstrating the potential value of this micron‐scale technique in studying and optimizing locally doped regions. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)