Gunn effects in InxGa1?xSb (0 ? x ? 0.16)

Gunn effects in InxGa1?xSb (0 ? x ? 0.16) have been observed. To observe the Gunn effect, a condition nL/n? ? 0.1 or, equivalently, ?EL? ? 6.4kT should be satisfied in the crystals. The threshold fields for the Gunn effect in the crystals were in the range of 0.6?1.0 kV/cm.     

Pulse generation in planar Gunn devices with varying nL product

Measurements of the current reduction in planar Gunn devices by domain nucleation are reported. The devices were made of epitaxially grown GaAs layers. The measurements showed a decrease of the current reduction, relative to the threshold current Ith, with decreasing nL product, beginning at about nL = 1013 cm?2, where n is the electron concentration and L is the length of active channel.     

Observations of high-field domains in GaxIn1 ? xSb Gunn diodes

The properties of high-field domains in GaxIn1-xSb Gunn diodes (0.4 < x < 0.82) have been studied by measuring the surface potential on the diodes. The domain velocities vary with the Ga composition x, 5.3?6.1×106 cm/s for0.8 > x > 0.55 and 10×106 cm/s for x = 0.4, but they are almost independent of the applied voltage, even if the electron concentration is increased by the impact ionisation in the domain at high applied voltages for the small-x samples.     

High-efficiency series operation of Gunn devices

Successful series operation of two Gunn devices, differing by about 10% in threshold current, has been achieved at X band (8.5?12GHz). The devices were mounted in a resonant cavity and biased to approximately six times the threshold voltage of a single device before both became active. At that point, the output power of the series combination was nearly equal to the sum of the powers observed previously for each device operating alone at its measured bias voltage. For one particular set of diodes, the observed efficiency (for series operation with N/f = 1.3 × 105 s/cm3) was 28.2% at 8.3GHz with 3.4W of peak pulsed power output. This is the highest efficiency ever reported for Gunn devices at such frequencies.     

基波注入锁定谐波耿氏振荡器研究

本文基于同步振荡器的非线性模型，导出了基波注入锁定二次谐波耿氏振荡器的锁定带宽表达式，完成了三毫米波段第二次谐波振荡器的基波注入锁定实验，理论分析与实验结果吻合。     

Coherent Gunn oscillations in Gaxin1?xSb

Gunn oscillations in GaxIn1?xSb were observed in the composition range 0.40 ? X ? 0.91. Negative resistance exists in the same composition range investigated. The threshold field for the current oscillation was in the range 430?790 V/cm.     

液封合成与切氏法生长InP单晶

——本文介绍一种制备InP单晶的新工艺.工艺特点是实验周期短和沾污少.晶体电学参数已达到N_D-N_A=4.53×10~(15)cm~(-3)和μ_(77K)=29920cm~2/V·s.(111)In面的位错密度为10~3～10~4cm~(-2).单晶锭重约200克.在掺Sn-InP衬底上汽相外延生长的InP层用于制做体效应器件,在58.3GHz下有120mW的输出功率和2.08%的效率.     

Effect of As4/Ga flux ratio on electrical properties of NID GaAs layers grown by MBE

The effect of the As4/Ga flux ratio R on NID GaAs layers has been studied when the MBE growth chamber is used without baking after reloading the arsenic cells, in order to increase the productivity of the system. In these conditions a change from p- to n-type is observed when R is varied from 1.8 to 14. Satisfactory p-type material is obtained at R ? 3 (p = 2.0 × 1014 cm?3, ?77 K = 6200 cm2 V?1 s?1). The maximum n-type mobility occurs at R = 5.8. Photoluminescence spectroscopy confirms the effect of R on the incorporation of residual impurities.     

Stability criterion for Gunn oscillators with heavy surface loading

The conditions for domain suppression in a Gunn diode with finite longitudinal and transverse dimensions are derived by studying the eigenfrequencies of the general wave solution of the system. For long samples a critical nd product holds, as well as an ?d product for the lowest-order oscillation frequency.     

Gunn effect bibliography

In view of the rapidly expanding interest and activity in the area of the Gunn effect, the following bibliography has been compiled for people who are studying or doing research in this area. The term "Gunn effect" is used, in general, to collectively describe a number of classes of bulk negative resistance behavior in semiconductors with energy band structures like that of GaAs. These modes of behavior include small-signal amplification, pure accumulation of space charge, mature dipole (true Gunn effect) mode. quenched accumulation (LSA) mode, and quenched dipole mode. These references deal with the theory, experimental results, and applications of the Gunn effect. Works of a fundamental nature concerning phenomena that are basic to all semiconductor behavior and other bulk negative resistance effects have not been included. Also, basic papers dealing with electron transport phenomena, such as hot electron theory and intervalley scattering, which are essential to a complete understanding of the Gunn effect and articles on the properties and band structure of GaAs, InP, CdTe, and other III-V compounds have not generally been included, although in certain cases they are listed if they have been frequently cited. As in the compilation of any bibliography, it is self-evident that some valuable and pertinent articles may have been overlooked.     

Increasing the locking bandwidth of a waveguide-cavity oscillator through the use of a double-tuned circuit

The experimental 6 GHz Gunn oscillator consists of a TE101 waveguide cavity and a coupling slot, both being mechanically tunable in frequency. Fractional-bandwidth?voltage-gain products of approximately 0.2, corresponding to Qext = 10, were obtained. Comparison is made with other broadband injection-locked solid-state oscillators.     

The Gunn effect in polar semiconductors

The main features of the Gunn effect can be accounted for by the transferred electron model of Ridley and Watkins, which predicts a bulk differential negative resistance and subsequent domain formation if electrons can be transferred sufficiently rapidly from the lowest conduction-band minimum to lower-mobility subsidiary minima. Experimental results forn-GaAs in verification of such a bulk negative resistance are presented. In the longer samples the current-time waveform consists of sharp spikes separated by flat valleys, as expected from the motion of domains. The voltage across the domains is found to scale with sample length as predicted; the value of the electric field inside the domain is estimated to be ≥60 000 V/cm, while the field outside is about 1500 V/cm. Gunn effect oscillations have also been observed inn-CdTe, but not inn-InSb orn-InAs. The absence of an instability in InSb and InAs is consistent with the transferred electron model, since the subsidiary minima in these materials are believed to be too high in energy to be populated before carrier multiplication occurs. Finally, it will be shown that unless the separation of the conduction-band minima is very small, the critical electric field at which the Gunn effect occurs is reasonably well predicted by the one-band polar optical mode runaway field.     

In0.53Ga0.47As liquid phase epitaxy on (100)-InP substrates at low growth temperatures

In0.53Ga0.47As epitaxial layers of high quality and excellent surface morphology have been grown in an automated LPE system. The growth temperature was varied between 500 and 63O°C. Room-temperature Hall measurements indicated a net carrier concentration of n = 8 × 1014 cm?3 and mobility values of ? = 13000 cm2V?1 s?1 at TG 617°C and n = 7.7 × 1015 cm?3 and ? = 9800 cm2 V?1 s?1 at TG = 517°C, respectively.     

Observation of negative differential resistance in In0.53Ga0.47As/InP:Fe JFETs

A negative differential resistance (NDR) is observed in the drain-current/drain-source-voltage characteristic of In0.53-Ga0.47As/InP: Fe JFETs with gate lengths of 2 ?m and 3 ?m at small forward-biased gate-source voltages. This phenomenon is explained by the existence of a stationary Gunn domain in the channel at the drain side edge of the gate.     

GaAs planar gunn devices with sulfur-ion implanted n layers

Planar type Gunn effect devices have been fabricated by sulfur-ion implantation into the Cr doped semi-insulating GaAs substrates. The high doping efficiency as 90% was obtained as a result of long heat treatment. The mobility of the sulfur-ion implanted n layers with average carrier concentration of 4 × 10¹⁶cm^?3 was 5200 cm²/Vsec at room temperature and 12,000 cm²/Vsec at 77 K. The minimum gate trigger voltage of the Gunn effect digital devices was 100 mV. Sulfur-ion implanted Gunn effect devices have shown superior current drop ratio dependence on doping-depth product, compared to the devices prepared from the epitaxial layer.     

Two-dimensional numerical analysis of stability criteria of GaAs FET's

Stability criteria of GaAs junction-gate FET's are studied by two-dimensional numerical analysis. The analysis covers the wide range of device geometry from the state of the art FET to the so-called Gunn effect digital devices. It is found that a GaAs FET exhibits either of the following three types of characteristics depending upon device geometry and doping concentration. First, for a thin channel with high doping concentration, the device tends to behave as a normal junction-gate FET with saturating current-voltage characteristics. This is even true when the n-l (device length) and n.d (device thickness) products exceed the previously accepted criteria for Gunn oscillation. Second, a stable negative resistance (SNR) is observed in devices with a moderate channel thickness. Third, for a thick channel, the device exhibits a Gunn oscillation with the domain propagating from the gate edge to the drain. These three categories of behavior are mapped on the nd plane with the help of simple analytic considerations. The map is found to compare well with experimental results.     

Note on the relationship between the domain-transit frequency and the cavity-controlled frequency of thin Gunn devices

Some measurements on thin Gunn devices mounted in cavities covering the range 7?20GHz are reported. For any particular device, it has been found that VBf is approximately constant, where VB is the bias voltage which gives maximum r.f. output at the frequency f. This observation has been related to the domain-transit frequency.     

Frequency/temperature characteristics of Gunn devices

The variability and large magnitude of the frequency/temperature coefficient of Gunn oscillators has limited the application of these devices. The letter outlines a program of experiments and computer simulations aimed at achieving an understanding of the basic ?f/?T mechanism and thus producing a deep stable oscillator. Our simulations successfully predict observed trends in the ?f/?T behaviour of Gunn devices with both alloyed metal and n+ regrown contacts. The results of our study show that stable oscillators with a small loaded Q factor and near maximum power output are realisable.     

Gunn effect in MESFET-like structures

The performance of planar field-effect controlled transferred electron oscillators with different combinations of layer thickness and doping concentration has been investigated. A negative differential resistance has even been obtained with 0.29 mu m thick 1.6*10/sup 17/ cm/sup -3/ n-doped samples. This is the first time a MESFET-like active layer has exhibited the Gunn effect and has successfully been operated as a TEO at 36 GHz.<>     

Equivalent circuit analysis of noise in bulk semiconductor devices

Equivalent transmission-line analogs may be developed to advantage for the analysis of noise in bulk semiconductor devices. We discuss first a transmission-line analog for the law of conduction and diffusion of a single species of charge carriers that experience small disturbances from equilibrium. Through the use of Nyquist's theorem it is possible to obtain the power spectra of the noise sources of the equivalent transmission-line circuit at thermal equilibrium. Next, an equivalent circuit can be obtained if there is more than one charge carrier. This circuit is generalized to the case of drifted carriers and applied to the metal-semiconductor-metal (MSM) diode and to the small-signal analysis of the Gunn effect. We show how the equivalent circuit for the Gunn effect gives, by inspection, a lower bound on the noise measure achievable with a Gunn diode. We find that the Gunn diode has noise measures exceeding the lower bound. A traveling-wave Gunn device achieves the lower limit.