Double-drift-region (p+pnn+) avalanche diode oscillators

The advantages of a double-drift-region avalanche diode oscillator are discussed. Conventional structures (p⁺nn⁺or n⁺pp⁺) are essentially single-drift-region devices in that transit-time delay (for IMPATT mode) and zone transit (for TRAPATT mode) occur in a single region of one impurity type. The proposed structure (p⁺pnn⁺) has two drift regions and is essentially two complementary avalanche diode oscillators in series.     

磷酸盐玻璃中稀土离子Ce~(3 )、Tb~(3 )、Er~(3 )和Tm~(3 )的能量转移和敏化过程的研究

本文报道了磷酸盐玻璃中Tb~(3 )和Ce~(3 )的浓度猝灭效应。在KrF激光(248毫微米,10毫微秒)激发下,测出磷酸盐玻璃中不同浓度Ce~(3 )或Tb~(3 )离子的荧光寿命。着重讨论了磷酸盐玻璃中Ce~(3 )→Tb~(3 )、Er~(3 )和Tm~(3 )的能量转移和敏化过程。     

偶氮苯聚合物薄膜光致表面调制效应研究（Ⅱ）

实验观测了DP-AN系列偶氮苯聚合物薄膜在Ar^ 激光（488nm）激发下的光致表面调制效应。给出488nm激光激发条件下,含有不同偶氮苯侧基的聚合物的光致表面调制效应的数值。在前文^[1]工作的基础上分析比较了DP-AN系列和BP-AN系列偶氮苯聚合物光致表面调制效应的不同及其产生的原因。给出影响偶氮苯聚合物光致表面调制效应的因素。     

Er3+-Yb3+ and Er3+ doped fiberlasers

Single-mode fiber lasers operating at ~1.57 μm are described. Output powers of >2 mW are reported for laser diode pumped operation. Direct comparison is made between fiber lasers using sensitized erbium (Er³⁺ and Yb³⁺) and erbium on its own. The performance of Er³⁺-Yb³⁺ fiber lasers is analyzed in more detail as a function of fiber length. Both CW and Q-switched operations are studied and the results obtained demonstrate that practical sources at 1.5 μm are available from diode pumped Er³⁺ -Yb³⁺ systems     

Effect of electron cyclotron resonance H+,Ne+, Ar+, and Xe+ plasma precleaning ontitanium silicide formation

A vacuum integrated cluster tool process incorporating electron cyclotron resonance plasma cleaning, Ti sputter deposition, and rapid thermal annealing in N₂ is used to form a TiN_x<1/TiSi_y bilayer on (100) Si where the film composition is controlled by the preclean chemistry. Chemical cleaning with nominal 10 eV H⁺ completely removes native Si oxide resulting in a hydrogen terminated surface that promotes silicidation compared to one cleaned with buffered-oxide-etching (BOE). If the native oxide is only partially reduced, viz., SiO_x<2 surface, for example by shortening the H⁺ exposure time, then silicidation is largely inhibited and a thicker nitride layer is formed. Sputter cleaning with 50 to 250 eV Ar⁺ results in a bilayer that is roughly equivalent to that formed with BOE, whereas 50 to 150 eV Xe⁺ bombardment favors nitridation. Precleaning with >150 eV Ne⁺ promotes silicidation, thereby minimizing nitride thickness. The effects of precleaning are significant as the activation energy for TiSi_y formation is reduced from 1.8 eV characteristic of a BOE cleaned surface to 1.2 eV on Si etched with 250 eV Ne⁺. Mechanistically, the silicide kinetics are shown to be inhibited by the presence of a thin amorphous layer that is formed only when cleaning Si with Ar⁺ and Xe⁺ with the effect that both knock-on oxygen atoms and implanted noble gas atoms trapped within the amorphous layer retard the requisite solid-phase epitaxial regrowth kinetics. Recrystallizing the amorphous Si surface prior to metallization appears to restore the near-normal silicide kinetics that is characteristic of Ne⁺ cleaning     

NaCl(OH-):(F2+)H色心激光的研究

文中报道了低温红外连续NaCl(OH-):(F2+)H色心激光的研究结果。当泵浦功率为4.5W,辅助光功率为34.5mW时,输出功率大于250mW,峰值波长为1.57μm。为保证色心激光稳定运转,必须要有辅助光。     

Tm3+/ Ho3+离子掺杂中红外超快激光技术研究进展（特邀）

稀土离子Tm3+/ Ho3+ 掺杂中红外2 μm波段超快激光由于广泛的应用前景成为近十余年来激光领域的研究热点之一。文中首先综述了稀土离子Tm3+/Ho3+掺杂固体/光纤2 μm波段超快激光锁模技术进展,包括主动锁模技术以及饱和吸收、克尔透镜、非线性偏振旋转、非线性光环形镜、非线性多模干涉等被动锁模技术;其次,结合激光增益介质及色散管理技术回顾了Tm3+/ Ho3+掺杂固体和光纤锁模激光脉冲宽度压缩进展;再次,总结了Tm3+/ Ho3+大能量/高功率超快激光技术及进展;最后,对2 μm波段超快激光发展趋势进行了总结和展望。     

MBE grown n+-i-δ(p+)-i-n+GaAs V-groove barrier transistor

The three-terminal n⁺-i-δ(p⁺)-i-n⁺V-groove barrier transistor (VBT) has been successfully fabricated by molecular beam epitaxy (MBE). The base terminal is connected to the δ(p⁺), the thin p⁺layer, by depositing aluminum on the etched V-groove. The demonstrated device possesses high potential of ultra-high-frequency (f_{r} > 30-GHz), high-power, and low-noise capability due to carriers transporting by thermionic emission and being controlled by the base-emitter bias.     

双掺(Ce~(3+)、Nd~(3+)):YAG晶体对撞脉冲锁模的研究

一、引 言 新晶体双掺(Ce~(3+)、Nd~(3+)):YAG是一种具有高转换效率的激光增益介质~[1],它利用Ce~(3+)、Nd~(3+)的敏化途径提高激光效率。晶体中的Ce~(3+)离予通过辐射和非辐射二种方式向Nd~（3+）转     

Infrared cross-section measurements for crystals doped withEr3+, Tm3+, and Ho3+

The absorption and emission cross sections of the transition between the ground spin-orbit multiplet and the lowest excited multiplet were measured for Er³⁺, Tm³⁺, and Ho³⁺ ions in a variety of crystalline hosts. The materials that were investigated include LiYF₄, BaY₂F₈, Y ₃Al₅O₁₂, LaF₃, KCaF₃ , YAlO₃, and La₂Be₂O₅. The absolute magnitudes of the emission cross sections were determined from the absorption spectra, with the aid of the principle of reciprocity. The calculated radiative emission lifetimes derived from these measured cross sections agree well with the measured emission decay times for most materials. The potential use of these rare-earth-doped materials in pulsed laser applications requires that the ground state exhibit adequate splitting to minimize the detrimental effects of the ground state thermal population, and also that the emission cross section be sufficiently large to permit efficient extraction energy. The systems based on Ho³⁺ in the eightfold coordinated sites of LiYF₄, BaY₂F₈, and Y₃Al₅O₁₂ appear to be the most promising     

直流辉光放电HgX(X=Cl,Br,I)B~2∑~+→X~2∑~+发射光谱的研究

蓝绿色激光由于在水下通讯等方面的应用近年来颇受重视,溴化汞激光就是其中的一种,连同氯化汞、碘化汞激光,统称为HgX(X=Cl,Br,Il)激光,其波长在可见波段一定范围内可调(HgCl:552～559nm,HgBr:495～505nm,HgI:443～445nm).激光跃迁B~2∑~+→X~2∑~+的上能态激发可由HgX_2蒸气在紫外光或快放电作用下分解实现:HgX_2→HgX_2(b~1∑_u~+)→HgX(B~2∑~+)+X(~2P).用后一种方式可制成小型、封闭、长寿命器件,但至今只能得到短脉冲(几+ns)输出.本文目的是通过研     

颜色可调Ca9NaZn(PO4)7:Ce3＋，Tb3＋荧光粉的发光性能研究

采用高温固相还原反应合成了新型单相荧光粉Ca ₉NaZn(PO₄)₇(CNZP):Ce³⁺,Tb³⁺,并对样品的发光性能和 能量传递过程进行分析。研究表明,在波长为310nm紫外光激发下, Ce³⁺、Tb3+ 双掺体系发射光谱同时包含Ce³⁺的宽带和Tb³⁺的 线状发射光谱;在CNZP体系中,Ce³⁺→Tb³⁺间能量传递的临界距离Rc=1.216nm,为共振能量传递,机理被证实为四 极子-四极子相互作用。从CIE色度坐标图可以看出,利用 能量传递效果和改变CNZP:0.02Ce³⁺,yTb³⁺中 掺杂离子的相对浓度可实现颜色从蓝紫色到绿色的调控,表明所得荧光粉在WLED用紫 外激发荧光粉中具有潜在的应用价值。     

Cr3+→Nd3+ energy transfer and Nd3+ laser action studies of La3Ga5SiO14:Cr3+,Nd3+ co-doped crystal

Energy transfer between Cr³⁺ and Nd³⁺ ions has been investigated in the 4.2-300-K temperature range by using steady-state and site-selective time-resolved laser spectroscopy. Radiative and nonradiative energy transfer has been studied from the time-resolved emission spectra and the donor fluorescence decays. The transfer efficiency was calculated as a function of temperature by using the Cr³⁺ lifetimes of the single doped and co-doped samples. Laser experiments were carried out in a diffusive cavity by pumping a co-doped rod 54 mm long and 5 mm in diameter with xenon flashlamps. The laser spectral emission shows a complex structure which varies as a function of pump energy. The temporal evolution of the laser spectrum is discussed in terms of a simple four-level spectral rate-equation laser model which takes into account the existence of two main broad Nd³⁺ site distributions with a large spectral overlap     

Na_2(b~3Σ_g~ )→Na_2(x~3Σ_u~ )发射光谱

用XeF激光的351毫米微来激励Na_2(x~1Σ_g~ )得到c~1Π_u→2~1Σ_g~ 跃迁范围内三条受激发射谱线及b~3Σ_g~ →x~3Σ_u~ 830毫微米至900毫微米准连续发射谱。文中讨论了这两个跃迁的关联并估计了产生激光振荡的可能性。     

BF2^＋注入对PMOS晶体管开启电压的影响

文章研究了BF2^ 注入对PMOS晶体管开启电压的影响,试验发现,在我们的工艺条件下,BF2^ 注入能量是影响PMOS管开启电压的主要因素,能量高于67．5kev的BF2^ 注入可导致开启电压正漂,而退火对开启电压正漂没有影响,F离子也没有促进B穿透。     

Spectroscopic Properties and Laser Performance of Er3+ and Yb3+ Co-Doped GdAl3(BO3)4 Crystal

An Er:Yb:GdAl₃(BO₃)₄ crystal was grown and room-temperature polarized absorption, emission, and gain spectra were investigated. Fluorescence decay curves of Er³⁺ at 1530 nm and Yb³⁺ at 1040 nm in the crystal were measured. Efficient laser operation of Er:Yb:GdAl₃(BO₃)₄ crystal at 1.5-1.6 mum was realized. Quasi-continuous-wave output powers of 1.8 W with slope efficiency of 19% and 0.78 W with slope efficiency of 14% were achieved in diode-pumped c-cut and c-cut and a-cut crystals, respectively. The output spectrum and polarization of Er:Yb:GdAl₃(BO₃)₄ laser were also investigated.     

Noise in near-ballistic n+nn+ and n+pn+ gallium arsenide submicron diodes

Direct-current (d.c.) characteristics and noise measurements in the range 1 Hz-25 kHz are reported for n⁺nn⁺ and n⁺pn⁺ near-ballistic devices, with n regions (p regions) of 0.4 μm (0.45 μm), fabricated by molecular beam epitaxy at Cornell. The n⁺nn⁺ mesa structures show very low 1/? noise. indicating a Hooge parameter α_H = 6.0 × 10^?. This very low noise is attributed to the near absence of phonon collisions. The thermal (? like) noise above 1 kHz is equal to Nyquist noise at the lowest currents, rising to slightly above Nyquist noise for high currents, indicating the presence of carrier drag effects. The n⁺pn⁺ noise, on the contrary, is quite high. It seems to be associated with the ambipolar effects occurring for low injection of electrons in the p region. The importance of noise measurements for confirming ballistic or near-ballistic behavior is discussed.     

Forward current—Voltage and switching characteristics of p+-n-n+(epitaxial) diodes

The forward-biased current-voltage and forward-to-reverse biased switching characteristics of p⁺-n-n⁺epitaxial diodes are investigated. The manner in which the n-n⁺junction affects the flow of injected minority carriers in the epitaxial region is characterized by a leakage parameter a. Experimentally, for diodes with epitaxial film widths much less than a diffusion length, a "box" profile accurately describes the injected minority carriers in the n region. The current is found to increase with increased epitaxial width at a fixed bias. A general switching expression for epitaxial diodes is presented and the validity of the expression is shown experimentally. The experimental values of a, determined independently from the current-voltage and switching characteristics, are in good agreement and show that the leakage of the high-low junction is dominated by the recombination of minority carriers in the n-n⁺space-charge region.     

Self-aligned silicided (PtSi and CoSi2) ultra-shallow p+/n junctions

Ultra-shallow p+/n junctions (<100 nm) demonstrating excellent I-V characteristics have been fabricated with self-aligned PtSi. Junctions were formed by rapid thermal annealing (RTA) 〈100〉 Si preamorphized with Sn+ and implanted with BF2+. Subsequently, low-temperature RTA in N2of sputter-deposited Pt produced a 55-nm-thick PtSi layer possessing a remarkably smooth surface and interface, and demonstrating excellent resistance to the aqua regia etch solution. The silicided junctions displayed a sheet resistance of 14 Ω/sq with less than -2-nA . cm^-2reverse-bias leakage at -5 V. In a comparative scheme, similar junction characteristics were obtained using a self-aligned 39-nm-thick CoSi2overlayer.