Carrier compensation in O+ implanted n-type GaAs

Results of electrical measurements on 1 MeV O⁺ implanted n-type GaAs are reported. After annealing the implanted material it is found that the free carrier compenasation rate (k), defined by Favennec[1] as the number of carriers removed per oxygen atom, can be dependent upon both the starting material and the implanted dose.     

Effects of diffused nickel on the silicon-silicon dioxide interface

The effects of diffused nickel on the interface of silicon and a thermally grown oxide are examined. Information regarding effective fixed charge at the interface, surface state distribution and surface state type, is derived from capacitance-voltage characteristics of metal-oxide-semiconductor capacitors made with nickel doped and non-nickel doped silicon. Nickel doping is shown to reduce the density of effective surface states with energies more than 0·15 eV below E_i, and to remove effective charge at the interface of the order of 0·1 μC/cm².     

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     

Collector-up HBT's fabricated by Be+and O+ion implantations

A novel collector-up (C-up) GaAs/AlGaAs heterojunction bipolar transistor (HBT) has been developed and initial device results presented. This device has its extrinsic base defined by Be + and O + implantations. The combination of Be + / O + implantations and heat-pulse annealing is leading to a considerable reduction in the parasitic current and capacitance in the extrinsic base region. Improved device structure and performance expected from this device are discussed in detail.     

Various effects of silicidation on shallow p+ junctionsformed by BF2+ implantation into thin poly-Sifilms on Si substrates

Various effects of silicidation on shallow p⁺ n junctions formed by the scheme that implants BF₂⁺ ions into thin poly-Si films on Si substrates are described. A post-Ni silicidation just slightly improves the preformed junctions of the annealed sample. However, as the sample is first deposited with thin Ni films after the implantation and then annealed, the resulting junctions are much better than the preformed ones. Moreover, as the sample is deposited with Ti films, the resultant junctions are just slightly better the preformed ones     

Effective recombination velocity at the NN+ interface

The effective recombination velocity S_nn⁺ at the nn⁺ interface in buried layer (nn⁺p) and n epi-n⁺ substrate structures has been studied using a model which takes into account the retarding outdiffusion region, recombination and bandgap narrowing. The variation of S_nn⁺ with diffusion length and bandgap narrowing has been estimated taking into consideration their doping-dependence. An attempt has been made to explain the wide range in the reported values for S_nn⁺ using the results of this study.Results indicate clearly the difference between the S_nn⁺ of the two structures. This difference arises from the collection by the p-substrate which accounts for a significant part of the S_nn⁺ of the buried layer structure over a wide range of values of diffusion length. This collection component of S_nn⁺ is sensitive to bandgap narrowing.On the other hand, the S_nn⁺ of the nn⁺ structure is largely determined by the recombination in the outdiffusion region which is sensitive mainly to the value of diffusion length in that region. The component of S_nn⁺ representing recombination in the n⁺ substrate is sensitive to bandgap narrowing. The present study indicates the dependence of S_nn⁺ on the structure and processing of the devices in which the nn⁺ interface occurs.     

Improved microwave performance on low-resistivity Si substrates bySi+ ion implantation

Microwave characteristics of spiral inductors on low-resistivity Si substrates have been improved by implanting Si₂₈⁺ ions. Spiral inductors fabricated on these implanted substrates demonstrate better Q-value and microwave performance. The Q-value of inductor enhanced 60% on the implanted substrates than that of low resistivity Si substrates. An equivalent circuit model of inductor has been evaluated to discuss the effect of substrate loss     

Rapid thermal annealing effects on Si p+-n junctionsfabricated by low-energy FIB Ga+ implantation

Effects of rapid thermal annealing (RTA) on sub-100 nm p⁺ -n Si junctions fabricated using 10 kV FIB Ga⁺ implantation at doses ranging from 10¹³ to 10¹⁵ cm ^-2 are reported. Annealing temperature and time were varied from 550 to 700°C and 30 to 120 s. It was observed that a maximum in the active carrier concentration is achieved at the critical annealing temperature of 600°C. Temperatures above and below the critical temperature were followed by a decrease in the active concentration, leading to a `reverse' annealing effect     

Deep trapping of implanted Na+ and Li+ ions near the Si/SiO2 interface in metal-oxide-silicon structures

Na⁺ and Li⁺ ions have been implanted in the oxide layer of MOS structures with doses ranging from 3 × 10¹¹ to 3 × 10¹³ ions/cm². Part of the implanted ions can be retraced as mobile ions: this fraction decreased with increasing dose. The trapping of the mobile ions near the Si/SiO₂ interface has been investigated by means of the thermally stimulated ionic current (TSIC) technique. The average energy depth of the ionic traps appeared to increase with increasing dose. Moreover, we found that Li⁺ ions are trapped deeper than Na⁺ ions under equivalent experimental conditions. The influence of the applied electric field on the detrapping has been studied. In the case of 3 × 10¹³ Na⁺ implantation, the barrier lowering corresponds with the Poole-Frenkel theory. We have also paid attention to the effects of bias-temperature stress treatments on the trapping kinetics. We observed a decrease of the mobile ion current after long BTS treatments.     

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     

A novel process to form cobalt silicided p+ poly-Sigates by BF2+ implantation into bilayeredCoSi/a-Si films and subsequent anneal

A novel process that implants BF₂⁺ ions into thin bilayered CoSi/a-Si films has been shown to form cobalt silicided p ⁺ poly-Si gates with excellent gate oxide integrity and very small flatband shift. The effects of not only using the CoSi layer as an implantation barrier but also keeping the a-Si underlayer during the initial silicide formation both significantly suppress the boron penetration through thin gate oxide     

Effect of i-layer parameters on the performance of Sin+-i-n+ homojunction far-infrared detectors

A unified formalism, including space-charge-limited (SCL) conduction, tunneling, and the multiple-image-force effect, is developed to perform a complete analysis of Si n⁺-i-n⁺ homojunction interfacial workfunction internal photoemission (HIWIP) FIR detectors. It is shown that due to the space-charge effect, the detector performance, such as cutoff wavelength (λ_c), quantum efficiency (η), dark current (I_d), noise equivalent power (NEP), etc., is strongly influenced by the i-layer thickness (W_i ) and compensating acceptor concentration (N_ai) in addition to the emitter layer parameters. As a result, the optimum operating conditions of detectors also depend on W and N_ai. The background limited performance (BLIP) is evaluated, and a critical W _i value is found for BLIP operation     

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。     

Suppression of cobalt silicide agglomeration using nitrogen(N2+) implantation

In this paper, the effects of nitrogen coimplantation with boron into p⁺-poly gate in PMOSFETs on the agglomeration effects of CoSi₂ are studied. The thermal stability of CoSi₂/poly-Si stacked layers can be significantly improved by using nitrogen implantation. Samples with 40-nm cobalt silicide (CoSi ₂) on 210-nm poly-Si implanted by 2×10¹⁵/cm ² N₂⁺ are thermally stable above 950°C for 30 s in N₂ ambient. If the dose of nitrogen is increased up to 6×10¹⁵/cm², the sheet resistance of CoSi₂ film is not increased at all, and TEM photographs show that the agglomeration of CoSi₂ film is completely suppressed     

A model for doped-oxide-source diffusion with a chemical reaction at the silicon-silicon dioxide interface

A mathematical model for doped-oxide-source diffusion is proposed. In this model the concept of segregation of impurity at the silicon-silicon dioxide is used and also a constant of “rate limitation” is introduced through a chemical reaction at the interface.     

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     

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     

Characteristics of siliconn+-n--n+ diode with sub-micrometer n- region

In this paper, the I-V characteristics of silicon n⁺-n ^--n⁺ diode are investigated as a parameter of the length of the n^- region. This diode with shorter n^- region than 1 μm has the ohmic characteristics until reaching high electric field in spite of the existence of numerous space-charges in the n^- region, for the first time in this report. This conductance of the diode is inversely proportional to the third power of the length of the n^- region. The experimental results are in good agreement with an analytical calculation including the diffusion term of carriers injected from the n+ regions to the n^- region. However, the diode with longer n^- region than 2 μm shows the space-charge-limited conduction which is the same as earlier reports     

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。     

双包层Er3+/Yb3+共掺光纤放大器动态特性研究

基于速率方程的离散算法,实现了对双包层Er3+/Yb3+光纤放大器动态特性的分析.研究了不同信号和泵浦功率下单信道的瞬态功率、脉冲序列输出功率与增益随时间的变化以及多信道异步转移模式下输出功率和增益随时间的变化.结果表明对于单个脉冲,在相同的泵浦功率下,输出脉冲的峰值功率取决于输入脉冲的峰值功率;在不同的泵浦功率下,输出脉冲的峰值功率取决于泵浦功率.对于脉冲序列,在达到稳定的输出前,将经历一个输出功率和增益由高到低的变化过程.对于异步转移模式的多信道脉冲,脉冲重叠时的功率和增益变化要快于非重叠时功率和增益的变化.