High-Performance Inversion-Type Enhancement-Mode InGaAs MOSFET With Maximum Drain Current Exceeding 1 A/mm

High-performance inversion-type enhancement- mode (E-mode) n-channel In_0.65Ga_0.35As MOSFETs with atomic-layer-deposited Al₂O₃ as gate dielectric are demonstrated. A 0.4-mum gate-length MOSFET with an Al₂O₃ gate oxide thickness of 10 nm shows a gate leakage current that is less than 5 times 10^-6 A/cm² at 4.0-V gate bias, a threshold voltage of 0.4 V, a maximum drain current of 1.05 A/mm, and a transconductance of 350 mS/mm at drain voltage of 2.0 V. The maximum drain current and transconductance scale linearly from 40 mum to 0.7 mum. The peak effective mobility is ~1550 cm²/V ldr s at 0.3 MV/cm and decreases to ~650 cm²/V ldr s at 0.9 MV/cm. The obtained maximum drain current and transconductance are all record-high values in 40 years of E-mode III-V MOSFET research.     

Electrical measurements of voltage stressed Al2O3/GaAs MOSFET

Electrical characteristics of GaAs metal–oxide–semiconductor field effect transistor with atomic layer deposition deposited Al₂O₃ gate dielectric have been investigated. The IV characteristics were studied after various constant voltage stress (CVS) has been applied. A power law dependence of the gate leakage current (I_g) on the gate voltage (V_g) was found to fit the CVS data of the low positive V_g range. The percolation model well explains the degradation of I_g after a high positive V_g stress. A positive threshold voltage (V_th) shift for both +1.5 V and +2 V CVS was observed. Our data indicated that positive mobile charges may be first removed from the Al₂O₃ layer during the initial CVS, while the trapping of electrons by existing traps in the Al₂O₃ layer is responsible for the V_th shift during the subsequent CVS.     

Comments on “High Performance Inversion-Type Enhancement-Mode InGaAs MOSFET With Maximum Drain Current Exceeding 1 A/mm”

We have a number of issues with the above paper ldquoHigh Performance Inversion-Type Enhancement-Mode InGaAs MOSFET With Maximum Current Exceeding 1 A/mm,rdquo by Y. Xuan, Y. Q. Wu, and P. D. Ye, published IEEE Electron Device Letters in April 2008 which we wish to highlight.     

Layered Al2O3-TiO2 compositedielectric resonators

Aluminium oxide displays a very low tanδ at microwave frequencies. It also possesses a remarkably high thermal conductivity, ideal for heat dissipation in high power satellite filters. However, its temperature coefficient of the resonant frequency (τ_f) is approximately 60 ppm/K. It is shown that the application of a film of titanium oxide which has a T_f of opposite sign (45O ppm/K) produces a composite in which the τ_f can be tuned to be zero over a wide temperature range. The tanδ of the composite at zero T_f is 3.3×10⁵ (Q=30000) at room temperature and at 10 GHz     

Dielectric thinning model applied to metal insulator metal capacitors with Al2O3 dielectric

The extrinsic fails of metal insulator metal capacitors (MIMCAPs) with Al₂O₃ dielectric are modeled by a thinning model that is based on the intrinsic reliability model and the assumption that the extrinsic fails behave like an intrinsic dielectric with a reduced thickness. The intrinsic reliability model is developed from voltage acceleration experiments at four temperatures and four dielectric thicknesses. Voltage and thickness dependence of the logarithm of the intrinsic lifetime scales with the electric field and the temperature dependence is described by an Arrhenius factor. The voltage acceleration is not temperature dependent. The thinning model is shown to consistently describe acceleration experiments with random extrinsic fails of unknown root cause at low defect density (0.1 cm⁻²) as well as a systematic extrinsic failure mechanism caused by process induced plasma damage. It is also shown that the random extrinsic fails that were investigated on large area teststructures can be extrapolated to much smaller product typical capacitors. A criteria based on the stored energy is derived that allows to decide, whether an extrinsic fail will cause product failure. These results allow a quantitative prediction of early product fails due to the MIMCAP.     

Single-frequency Ti:Al2O3 ring laser

Over 500 mW of single-frequency power has been obtained from a Ti:Al₂O₃ ring laser pumped by 10 W (all lines) from an argon ion laser. The ring laser can be tuned from 750 to 850 nm while maintaining more than 100 mW in single-frequency operation without realignment or a change of optics. The free-running frequency stability of the laser is 3 MHz. Thermal effects cause changes in the ring cavity parameters, limiting the output power. This ring laser has also been operated with an acoustooptic mode locker to obtain 200-ps mode-locked pulses at 250 MHz with nearly the same average power as in single-mode operation     

Electrical and interfacial characteristics of nanolaminate (Al2O3/ZrO2/Al2O3) gate stack on fully depleted SiGe-on-insulator

The structural and electrical characteristics of a novel nanolaminate Al₂O₃/ZrO₂/Al₂O₃ high-k gate stack together with the interfacial layer (IL) formed on SiGe-on-insulator (SGOI) substrate have been investigated. A clear layered Al₂O₃ (2.5 nm)/ZrO₂ (4.5 nm)/Al₂O₃ (2.5 nm) structure and an IL (2.5 nm) are observed by high-resolution transmission electron microscopy. X-ray photoelectron spectroscopy measurements indicate that the IL contains Al-silicate without Ge atom incorporation. A well-behaved C–V behavior with no hysteresis shows the absence of Ge pileup or Ge segregation at the gate stack/SiGe interface.     

High-density MIM capacitors using Al2O3 andAlTiOx dielectrics

We have investigated the electrical characteristics of Al₂ O₃ and AlTiO_x MIM capacitors from the IF (100 KHz) to RF (20 GHz) frequency range. Record high capacitance density of 0.5 and 1.0 μF/cm² are obtained for Al₂ O₃ and AlTiO_x MIM capacitors, respectively, and the fabrication process is compatible to existing VLSI backend integration. However, the AlTiO_x MIM capacitor has very large capacitance reduction at increasing frequencies. In contrast, good device integrity has been obtained for the Al₂O₃ MIM capacitor as evidenced from the small frequency dependence, low leakage current, good reliability, small temperature coefficient, and low loss tangent     

A Ti:Al2O3 master-oscillator/power-amplifiersystem

The authors have constructed a multistage Ti:Al₂O₃ master-oscillator/power-amplifier system which generates 115-ns, 0.38-J pulses at 800 nm. The system is tunable from 760 to 825 nm and has a repetition rate of 10 Hz. Measurements of the output pulse demonstrate near-diffraction-limited performance and a Fourier-transform-limited bandwidth of ~4 MHz     

增强型InGaP／AlGaAs／InGaAs PHEMT栅退火工艺

针对InGaP/AlGaAs/lnGaAs PHEMT器件,进行了Ti/Pt/Au和Pt/Ti/Pt/Au两种栅金属结构的退火实验,通过实验研究比较,得到了更适用于增强型器件的退火工艺,利用Ti/Pt/Au结构,在320℃退火40min,使器件阈值电压正向移动大约200mV,从而成功制作了高成品率的稳定一致的增强型器件,保证了增强型器件阈值电压在零以上.     

MgO-Y_2O_3对热压烧结Al_2O_3性能的影响

以高纯的硫酸铝氨分解的无定形Al2O3为原料,MgO-Y2O3为烧结助剂,在N2气氛下热压烧结制备Al2O3陶瓷。研究了烧结助剂掺量对Al2O3材料的相组成、显微结构、烧结性能、力学性能、热导率和介电性能的影响。结果表明:所制Al2O3陶瓷具有细晶的显微结构特征和超高的抗弯强度。随着MgO-Y2O3掺量的增加,晶粒尺寸、抗弯强度和热导率先增大后减小,而介电损耗则呈现先减小后增大的变化规律。当MgO和Y2O3掺量均为质量分数2%时,Al2O3陶瓷呈现为较佳的综合性能:抗弯强度达最大值为603 MPa,热导率为36.47 W.m–1.K–1,介电损耗低至6.32×10–4。     

Dielectric properties of single crystals of Al2O3, LaAlO3, NdGaO3, SrTiO3, and MgOat cryogenic temperatures

A dielectric resonator technique has been used for measurements of the permittivity and dielectric loss tangent of single-crystal dielectric substrates in the temperature range 20-300 K at microwave frequencies. Application of superconducting films made it possible to determine dielectric loss tangents of about 5×10^-7 at 20 K. Two permittivity tensor components for uniaxially anisotropic samples were measured. Generally, single-crystal samples made of the same material by different manufacturers or by different processes save significantly different losses, although they have essentially the same permittivities. The permittivity of one crystalline ferroelectric substrate, SrTiO₃, strongly depends on temperature. This temperature dependence can affect the performance of ferroelectric thin-film microwave devices, such as electronically tunable phase shifters, mixers, delay lines and filters     

Stack gate PZT/Al2O3 one transistorferroelectric memory

We have developed a single transistor ferroelectric memory using stack gate PZT/Al₂O₃ structure. For the same ~40 Å dielectric thickness, the PZT/Al₂O₃/Si gate dielectric has much better C-V characteristics and larger threshold voltage shift than those of PZT/SiO₂/Si. Besides, the ferroelectric MOSFET also shows a large output current difference between programmed on state and erased off state. The <100 us erase time is much faster than that of flash memory where the switching time is limited by erase time     

增强型InGaP/AlGaAs/InGaAs PHEMT栅退火工艺

针对InGaP/AlGaAs/lnGaAs PHEMT器件,进行了Ti/Pt/Au和Pt/Ti/Pt/Au两种栅金属结构的退火实验,通过实验研究比较,得到了更适用于增强型器件的退火工艺,利用Ti/Pt/Au结构,在320℃退火40min,使器件阈值电压正向移动大约200mV,从而成功制作了高成品率的稳定一致的增强型器件,保证了增强型器件阈值电压在零以上.     

Improved retention characteristic of charge-trapped flash device with sealing layer/Al2O3 or Al2O3/high-k stacked blocking layers

Although programming and erase speeds of charge trapping (CT) flash memory device are improved by using Al₂O₃ as blocking layer, its retention characteristic is still a main issue. CT flash memory device with Al₂O₃/high-k stacked blocking layer is proposed in this work to enhance data retention. Moreover, programming and erase speeds are slightly improved. In addition, sealing layer (SL), which is formed by an advanced clustered horizontal furnace between charge trapping layer and Al₂O₃ as one of the blocking layers is also studied. The retention characteristic is enhanced by SL approach due to lower gate leakage current with less defect. With the combination of SL and Al₂O₃/high-k stacked blocking layer approaches, retention property can be further improved.     

采用ALD Al2O3作为栅介质的薄势垒增强型AlGaN/GaN MIS-HEMT

本文报道了高性能的增强型（E-mode）氮化镓（GaN）基金属-绝缘体-半导体高电子迁移率晶体管（MIS-HEMT）,该器件势垒层为5-nm厚的铝镓氮（Al0.3Ga0.7N）,并采用氮化硅（SiN）钝化来控制二维电子气（2DEG）密度。与SiN钝化不同,采用原子层淀积（ALD）技术生长的氧化铝（Al2O3）不会增强异质结中的2DEG密度。刻蚀栅区的SiN介质可以耗尽沟道电子,之后采用ALD Al2O3作为栅介质,可以实现MIS结构。栅长为1 μm的E-mode MIS-HEMT具有657mA/mm的最大饱和电流（IDS）、187mS/mm的最大跨导（gm）和1V的阈值电压（Vth）。与相应的E-mode HEMT对比,由于Al2O3栅介质的引入,使器件的性能得到了很大的提升。本文对于同时实现高的Vth和IDS提供了很好的方法。     

钛宝石的晶体生长与性能

本文采用提拉法生长出了高光学质量的Ti:Al2O3单晶,讨论了生长和退火工艺对晶体质量的影响。在室温条件下,14.8mm长的TiAl2O3激光棒,以35mJ的Nd:YAG倍频激光泵浦,在带有色散元件的激光腔中,获得了6.4mJ(780nm)激光输出,激光效率为18%。     

A Miniature Dual-Mode Bandpass Filter Using Al2O3 Substrate

A dual-mode bandpass filter using the degenerate modes of a modified square ring structure printed on the high-permittivity substrate is proposed. The dual-mode resonator is based on a square ring loaded with a cross-strip. The filter is printed on the Al₂O₃ substrate with a permittivity of 9.8 and could be easily integrated with radio frequency circuits. Besides its simple structure, the filter shows low insertion loss and small size, owing to the high-permittivity substrate used. The proposed filter shows a size reduction of 44% compared with the case using a simple cross-strip, and it also provides transmission zeros on both sides of the bandwidth. Experimental results are in good agreement with simulated values.     

A 6.5-J flashlamp-pumped Ti:Al2O3 laser

A flashlamp-pumped Ti:A₂O₃ oscillator has delivered 6.5 J per pulse at 800 nm under long-pulse extraction conditions. The device was designed for efficient short-pulse (2-3 ns) amplification to the multijoule energy level. To date, a peak stored energy in excess of 5 J has been obtained and is available for short-pulse extraction studies. The design and resulting characterization of this laser are discussed. The results show that the energy available for short-pulse extraction is limited by the flashlamp pumping time     

高反Al2O3/SiO2膜内超快激光预损伤动力学过程

利用紫外飞秒激光光谱技术研究了Al2O3/SiO2高反射膜内的超快载流子动力学。通过实验,发现该反射膜Al2O3层的载流子动力学在紫外反射膜的激光诱导损伤中起着至关重要的作用。通过泵浦-探测实验,发现紫外飞秒激光与光学薄膜作用后,光学薄膜反射率有所下降,且探测光反射率变化的峰值在约2.3 ps的时间内从417 nm左右转移到402 nm左右。为了更好的解释激光诱导载流子动力学,一个具体的理论模型被提出来,该模型指出导带自由电子弛豫过程中与晶格相互作用,产生距导带一个光子能量的中间缺陷态,其初始电子密度影响了材料损伤阈值高低。通过该理论模型得出的激光损伤阈值数据和实验数据吻合得很好。