Ion implanted GaAs varactor diodes: capacitance uniformity

Gallium arsenide varactor diodes with low series resistance (~0.25 ?) for u.h.f. t.v. tuners are developed. Uniformity and reproducibility of diode capacitance is improved markedly by using improved ion implantation and l.p.e. techniques. The standard deviation of diode capacitance distribution is 0.74% at V = 3.0 V within a wafer. A good r.f. tracking characteristic can be obtained in varactor tuners.     

U.H.F. low-noise GaAs m.e.s.f.e.t. amplifier for colour t.v. broadcasting translator

Low-noise amplifiers for u.h.f. colour t.v. broadcasting translator use have been successfully developed by using 1 ?m gate GaAs m.e.s.f.e.t.s. The obtained performances revealed that a GaAs m.e.s.f.e.t. has low-noise and low intermodulation distortion characteristics, even in the 500?800 MHz frequency range, compared with a Si bipolar transistor.     

Degradation mechanism of Ti/Au and Ti/Pd/Au gate metallizations in GaAs MESFET's

Modifications of several dc parameters of GaAs MESFET's induced by accelerated aging at 300 °C have been investigated in a test pattern configuration. Two different gate metallization structures have been examined, namely GaAs/Ti/Au and GaAs/Ti/Pd/Au. The gate diode and the MESFET characteristics of the former degrade noticeably upon annealing, while they are less affected by the thermal treatments for the latter. This different behavior is probably induced by the formation of different compounds at the metal-GaAs interface, which modify the gate diode properties.     

Laser-emission noise and voltage noise of GaAs c.w. laser diodes

The statistical intensity fluctuations (noise) of the total light output from c.w. GaAs laser diodes operated above the lasing threshold at 77°K have been measured as a function of the diode current. The noise voltage appearing across the laser diode has also been measured for diode currents above the lasing threshold.     

一种改进结构的GaAs微波PIN二极管

设计并制作了高性能GaAs微波PIN二极管.分析了GaAsPIN二极管的结构对其性能的影响,并根据分析结果改进了GaAsPIN二极管的结构.制作了常见结构和改进结构的GaAsPIN二极管,比较了不同结构的GaAsPIN二极管的测试数据,从而验证了理论分析的结果.改进后的GaAsPIN二极管制作工艺更为简单,具有良好的高频特性,截止频率达到1520.5GHz.这种改进结构的GaAs微波PIN二极管在微波电路中具有良好的应用前景.     

Frequency Dependent Capacitance and Conductance–Voltage Characteristics of Nitride GaAs Schottky Diode

Semiconductors - A nitride GaAs Schottky diode have been fabricated by nitridation of GaAs substrates with thickness 0.7 nm of GaN layer. The capacitance–voltage C(V) and...     

Avalanche noise in GaAs m.e.s.f.e.t.s

Instabilities in the d.c. characteristics of GaAs m.e.s.f.e.t.s for drain to source voltages greater than 4 V. believed to be due to reloading of traps in the interface between active layer and bulk material, or gunn-domain formation, seem to have their origin in avalanche breakdown of the back diode under the drain contact. Microplasma switching, vertical to the active layer, strongly modulates the drain current producing large broadband noise power.     

High-Q GaAs varactor diodes

A double epitaxial gallium arsenide tuning diode has been developed for TV varactor tuners. The capacitance variation ratio is 6.0 and is large enough to cover the UHF TV broadcasting band. Diode series resistance is 0.18 Ω (Q = 200) at 470 MHz, and at a capacitance of 9 pF. This resistance is 4.4 times smaller than Si diodes in its mean value. Contribution of each resistance component to the total diode resistance was studied. The result shows that package loss is 0.11 Ω, RF skin-effect resistance is 0.05 Ω, and the undepleted epitaxial layer resistance is 0.048 Ω. Therefore, a diode with a 0.075-Ω (Q = 480) series resistance at 470 MHz could be developed, if package loss and RF skin-effect resistance are improved.     

Diode structures from amorphous low-temperature GaAs

The effect of annealing on the electrical properties of a GaAs diode structure, which incorporated a nominally undoped low-temperature (LT) layer on top of conventionally grown p-type GaAs, is examined. Unannealed GaAs grown by molecular beam epitaxy at substrate temperatures below 250°C is amorphous and highly resistive. Annealing at high temperatures converts the undoped LT-GaAs from amorphous to single crystal material. The annealed material is n-type. The current-voltage characteristics of the LT on p-type GaAs structures showed greater asymmetry, with lower reverse leakage currents, as the anneal temperature was increased above 400°C. This reflects the improved crystal quality of the LT layer.     

Effects of laser irradiation of GaAs observed by d.l.t.s.

A Q-switched ruby laser has been used to heat-treat vapourphase-epitaxial (v.p.e.) GaAs. The characteristic A-centre, a deep trapping level at 0.83 eV, is removed using a laser pulse of energy density 0.3 J cm?2. Trapping levels are observed using deep-level transient spectroscopy (d.l.t.s.).     

Improvement of GaAs/AlGaAs quantum well laser diodes by rapid thermal annealing

Post-growth annealing is shown to improve the laser diode quality of GaAs/AlGaAs graded-index separate confinement heterostructure quantum well laser diode structures grown at a nonoptimal substrate temperature lower than 680°C by molecular beam epitaxy. Reduction by a factor of up to three in the threshold current was accompanied by a reduction in the interface trap density. The reduced threshold current is still higher than that of laser diodes grown at the optimal temperatures which are between 680 and 695°C. The improvement in laser diode performance is ascribed to the reduction of interface nonradiative recombination centers.     

Limitations of the back-to-back barrier-intrinsic-n+(BIN) diode frequency tripler

Problems of the back-to-back GaAs barrier-intrinsic-n⁺ (BIN) diode frequency tripler concept along with the associated device physics are presented. The back-to-back GaAs BIN diode structure was originally proposed to have an intrinsic cutoff frequency close to 1 THz and to be a highly efficient millimeter-wave frequency tripler. Frequency limitations will be discussed to explain the failure of the back-to-back GaAs BIN diode as a millimeter-wavelength device. Optimization is also carried out to explore the possibility of improving the high-frequency performance by modifying the BIN diode structure     

Comparison of GaAs MESFET and GaAs p-i-n diodes as switch elements

The Kurokawa-Schlosser quality factor Q̂ is used to compare the GaAs MESFET switch with the GaAs p-i-n diode switch. The MESFET device parameters are governed by the power handling capability and the specified pinchoff voltage, and the switch Q̂ is calculated from an approximate expression. The GaAs p-i-n has been characterized using a simple diode model which is derived from detailed simulations. The comparison for typical devices shows that the GaAs pin has the higher Q̂ and therefore should have improved characteristics as a switch in terms of insertion loss and isolation.     

Measurement of Richardson constant of GaAs Schottky barriers

The Richardson constants for near-ideal AuGaAs and AlGaAs Schottky diodes have been determined from an analysis of forward current-voltage characteristics. Measurement of capacitance-voltage characteristics at different temperatures shows that the barrier heights of the diodes have very similar temperature dependence for both Au and Al contacts. On taking into account the temperature dependence of the barrier height, the corrected value of the Richardson constant for AuGaAs diode is found to be very close to the predicted theoretical value. The corresponding value for AlGaAs diode is about a factor of five smaller which is explained on the basis of a thin interfacial layer between Al and GaAs.     

GaAs垂直结构PIN二极管限幅器

基于垂直结构GaAs PIN二极管的工艺技术开发,在GaAs PHEMT生产线上开发研制了GaAs PIN二极管限幅器单片集成电路.针对不同频段的单片电路采用了不同的材料结构参数设计.工艺中采用先进的深挖槽技术,严格控制横向钻蚀问题,制作出了限幅水平40 mW、最大承受功率5 W的多个频段GaAs限幅器单片电路,成品率达到95%以上.GaAs垂直结构PIN二极管工艺对GaAs PIN二极管大功率开关、限幅器等GaAs MMIC的发展具有重大意义.     

Noise considerations for a tunnel diode integrated rectangular patch antenna

The tunnel diode integrated rectangular patch antenna is investigated, with emphasis mainly on noise considerations. Noise power is calculated and is found to increase very slightly with frequency for both GaAs and Ge tunnel diode loaded patches. Noise figure and noise temperature also increase with frequency for GaAs and Ge tunnel diode loaded patches. Loading the patch with the tunnel diode increases the effective noise figure and effective noise temperature of the patch, degrading the performance of the communication system significantly.     

Microwave power amplification with InP f.e.t.s

InP f.e.t.s were fabricated from v.p.e. layers, with an Al gate of 1.5 ?m × 308 ?m. The power output at 9 GHz, with 4 dB gain, was 1.15 W/mm gate width. This result is believed to be higher than the best published results obtained with equivalent GaAs f.e.t. structures.     

1~26.5GHz GaAs PIN单刀单掷开关单片

采用GaAs PIN二极管,完成1~26.5 GHz的单刀单掷开关单片的设计、制作。SPST开关单片带内插损小于0.5 dB,驻波优于1.1,隔离度大于27 dB,在10~26.5 GHz,隔离度大于37 dB。开关单片采用MOCVD生长的GaAs纵向PIN二极管材料结构,76 mm GaAs圆片工艺加工制作。     

八毫米GaAs梁式引线肖特基势垒混频管

基于Pucel平面电容器模型和Berger平面电阻器的传输线模型(TLM),借助CAD技术,优化设计了平面型八毫米粱式引线混频管的几何参数,确定了关系到器件性能的几个关键尺寸 L_g、W_g、L_o和 L_b对总电容和串联电阻的影响.采用了类似于GaAs MESFET的制作工艺,并严格控制器件的几何参数.研制的八毫米混频管,典型结果是,在35GHz下,单管双边带噪声系数为4.8dB.