Low frequency characteristics of a quasioptical Schottky diode detector part I: Theory

A theoretical study is made of saturation effects of FIR point contacts Schottky diodes when used in the envelope detection mode of operation. A model is described that fits experimental results for radiation wavelength ranging from microwaves down to FIR wavelengths. This model permits the prediction of saturation levels throughout this range.     

Heterodyne performance of a quasioptical Schottky diode detector: Theoretical and experimental results

A detailed theoretical and experimental study of the heterodyne performance of a quasioptical Schottky diode detector is presented. The experimental results have been obtained by mixing the radiation from a FIR laser with the output of a 67–73 GHz Klystron. The heterodyne signal variation versus various parameters and its relation to the special case of two lasers mixing are described. The mixer characteristics are a NEP value of 2×10^?19W/Hz and a detector bandwidth of at least 9 GHz. Experimental evidence of harmonics generation of submillimetric frequencies at the diode junction is also presented.     

Low frequency characteristics of a quasioptical schottky diode detector. Part III: Higher order theory

A higher order theoretical model is presented to describe the behaviour of FIR point contact Schottky diodes for high signal levels and/or high bias currents. This model includes non-linear perturbation on the voltage induced at the Schottky junction. Its fit to experimental results in case of envelope detection is also discussed and compared to the fit determined with our previous non-perturbation theory.     

Experimental results of a high Q quasioptical reflection cavity

A quasi-optical reflection cavity intended to be used as the resonant load of a submillimeter wavelength oscillator has been designed, constructed, and tested. The resonator consists of three elements in cascade: a high Q, high finesse folded Fabry-Perot resonator, a lower Q, low finesse Fabry-Perot resonator, and a Littrow mounted diffraction grating. The resonator exhibits a Q of 6600 and 2.5 dB of loss at 63 GHz. The design can be scaled to 1 THz, where waveguide structures become impractical, to serve as the resonator for high frequency quantum well resonant tunneling device oscillators.     

基于肖特基二极管的太赫兹准光探测器设计方法与成像性能研究

设计了一款太赫兹准光探测器, 该探测器主要由砷化镓肖特基二极管芯片以及高阻硅透镜组成.为了减小所设计芯片的欧姆损耗, 将天线图案生长在了半绝缘砷化镓层上.在335～350GHz频率范围内, 准光探测器的实测电压响应率为1360～1650V/W, 双边带变频损耗为10.6～12.5dB.对应估算的等效噪声功率为1.65～2pW/Hz1/2.基于所设计的准光探测器进行了成像实验, 该实验分别在直接检波和外差探测两种模式间进行, 成像结果表明所设计的太赫兹准光探测器能够满足太赫兹成像方面应用.     

基于零偏置肖特基二极管的270 GHz高性能波导检波器

根据InP二极管的物理结构, 采用三维高频电磁仿真软件对其精确建模仿真, 获得二极管的物理模型和匹配电路的精确参数, 而后将此模型利用谐波平衡进行仿真设计.最后, 在此基础上采用InP肖特基二极管, 设计制作并测试了国内首款270GHz的零偏置检波器.检波器的最大电压响应度为1600V/W, 在260~280GHz范围内, 电压响应的典型值为1400V/W, 其对应的等效噪声功率典型值为18pW/Hz.实验结果与仿真结果比较吻合, 其结果表明, 设计方法较为精确, 具有设计简单、优化方便等优点.     

Schottky diode characteristics of Ti on strained-Si

The Schottky barrier height and ideality factor of Ti on p-type strained-Si (grown on a graded relaxed Si_0.82Ge_0.18 buffer layer) were investigated in the temperature range 200–300 K using the current-voltage (I-V) characteristics and were found to be temperature dependent. While the ideality factor decreases with an increase in temperature, the barrier height increases.     

A high cutoff frequency planar Schottky diode with a stripe geometry junction

Design and experimental results of a planar Schottky-barrier diode suitable for use in MIC's are presented. The Schottky junction has a stripe geometry with a closely located ohmic contact. This geometry is effective in reducing the skin-effect parasitic resistance to yield a high cutoff frequency. The experimental diode has been fabricated using n and n⁺GaAs layers selectively grown on a semi-insulating substrate. A zero-bias cutoff frequency of more than 700 GHz has been obtained.     

Fabrication and characteristics of a 4H-SiC junction barrier Schottky diode

4H-SiC junction barrier Schottky(JBS)diodes with four kinds of design have been fabricated and characterized using two different processes in which one is fabricated by making the P-type ohmic contact of the anode independently,and the other is processed by depositing a Schottky metal multi-layer on the whole anode.The reverse performances are compared to find the influences of these factors.The results show that JBS diodes with field guard rings have a lower reverse current density and a higher breakdown voltage,and with independent P-type ohmic contact manufacturing,the reverse performance of 4H-SiC JBS diodes can be improved effectively. Furthermore,the P-type ohmic contact is studied in this work.     

4H-SiC结型势垒肖特基二极管的制作与特性研究

本文设计制作了两种具有不同结构参数的4H-SiC结型势垒肖特基二极管,在制作过程中采用了两种制作方法：一种是对正电极上的P型欧姆接触进行单独制作,然后制作肖特基接触的工艺过程;另一种是通用的通过一次肖特基接触制作就完成正电极制作的工艺过程。器件制作完成后,通过测试结果比较了采用场限环作为边界终端与未采用边界终端的器件的反向特性,结果显示采用场限环有效地提高了该器件的击穿电压,减小了其反向电流。另外,测试结果还显示采用独立制作P型欧姆接触的工艺过程有效提高了4H-SiC结型势垒肖特基二极管的反向特性,其中P型欧姆接触的制作过程和结果也在本文中做出了详细叙述。     

A study of Pd/Si MIS Schottky barrier diode hydrogen detector

Pd/Si MIS Schottky diode hydrogen detectors have been fabricated with a response of 2-3 orders of magnitude change in current for 154 ppm of H2in N2. Detailed evaluation of dark I-V, C-V, illuminated I-V, and internal photoemission data unambiguously ascribes the strong hydrogen sensitivity of these diodes to hydrogen-induced change in the work function of Pd, rather than to any surface-state effects. The reaction rate of the device to different gas ambients has been studied with time response measurements. A long-term degradation mechanism has been identified and traced to the poisoning of Pd by environmental sulfur. The role of oxygen and atomic hydrogen in determining the Schottky barrier height also is discussed in some detail.     

Electrical characteristics of an epitaxial high barrier Schottky diode

A Schottky barrier diode with high barrier height injects minority carriers at the forward biased condition. With injection of minority carriers the current density–voltage characteristics are altered significantly from that of the conventional exponential relationship. A model incorporating drift and diffusion currents for both holes and electrons, carrier recombination within the drift region and also the blocking properties of the low–high (n^- n⁺) interface is developed. The previous works on high barrier Schottky diodes used empirical expressions to combine the high injection model with the low injection model in order to study its behaviour at intermediate levels of injection. Whereas in the present work, a boundary condition is applied to combine the high injection model with an intermediate injection model. To combine an intermediate level model with a low injection level model, another boundary condition is introduced. The present work provides solutions for important physical quantities such as the minority carrier profile and current within the drift region, injection ratio and storage time.     

The near field of dipole antennas, part II: Experimental results

The results of an experimental program to evaluate the electric field near dipole antennas are presented. The measured field intensities are compared with the numerical values computed using the theory developed in Part I of this paper. The theoretical and measured field intensities are in excellent correlation even for observation points spaced from the axis of the dipole less than one hundredth of a wavelength. For thin dipoles (radius ≃ .002λ) the experimental measure of the E-field at the antenna surface or at one antenna radius distance has not been possible because of the practical limitation of available instruments. The experimental and theoretical results show that the field intensities near some parts of a dipole antenna are higher than predicted by commonly used formulas.     

Temperature dependence of Schottky diode characteristics prepared with photolithography technique

A Richardson constant (RC) of 8.92 Acm^?2K^?2 from the conventional Richardson plot has been obtained because the current–voltage data of the device quite well obey the thermionic emission (TE) model in 190–320 K range. The experimental nT versus T plot of the device has given a value of T₀ = 7.40 K in temperature range of 160–320 K. The deviations from the TE current mechanism at temperatures below 190 K have been ascribed to the patches introduced by lateral inhomogeneity of the barrier heights. Therefore, an experimental RC value of 7.49 A(cmK)^?2 has been obtained by considering Tung’s patch model in the temperature range of 80–190 K. This value is in very close agreement with the known value of 8.16 Acm^?2K^?2 for n-type GaAs.     

Static characteristics of high-barrier Schottky diode under high injection level

Static J–V, σ–J, γ–J characteristics based on numerical 1D simulation for Me–n–n⁺ and Me–n structures are given. The forward voltage drop of the former structure is less then the last one under high level injection because of LH (nn⁺) junction reflecting properties with respect to minority carriers. Holes stimulate base conductivity modulation but, in spite of this, the hole current gives a negligible contribution to the total current. It is shown that the injection ratio is a less significant parameter compared to base conductivity modulation if it is necessary to estimate charge storage. Influence of substrate is investigated. In addition to forming an LH barrier, the substrate acts as a source of majority carriers and defines the forward voltage drop across the diode structure. Bandgap narrowing in the substrate is taken into account. A comparison with experimental results is also given.     

Effect of deep impurity levels on Schottky barrier diode characteristics

In the presence of an arbitrary number of deep donor levels volt-ampere and volt-farad characteristics are obtained for the Schottky barrier diode which contains a thin dielectric layer between the metal and the semiconductor. The analysis of these characteristics shows that the deep levels can significantly influence both the capacitance and the rectifying properties of the Schottky diode; the thicker the dielectric layer, the greater the effect of the deep levels upon volt-ampere relationship and the lesser upon volt-farad one. One can determine the parameters of the deep levels from these relationships. The results of the calculation are in agreement with the data of the experiment performed.     

Continuous-wave frequency synthesis of a laser diode based ondiscrete-time negative frequency feedback: II. Theory

For part I, see, ibid., vol. 31, no.6, p. 1038, 1995. In this paper, we present the theory for a novel lightwave frequency synthesis system demonstrated recently. The system is composed of a frequency stabilized master laser, a frequency tunable slave laser, and an active optical feedback loop with an acoustooptic frequency shifter. The reference frequency is synthesized by circulating the optical pulse from the master laser around the loop and one output pulse with the desired frequency shift is used to stabilize the frequency of the slave laser. The theoretical aspects of the frequency synthesis system are explained based on the control theory for discrete-time negative feedback. We evaluate the frequency stability numerically by means of the Allan variance for different sampling periods, and reveal the relation between the frequency fluctuation characteristics of the slave laser in its free running condition. The numerical results agree with those of the reported experiments     

Fabrication and electrical characteristics of Schottky diode based on organic material

The current-voltage (I-V), capacitance-voltage (C-V) and capacitance-frequency (C-f) characteristics of Al/Orange G/n-Si/AuSb structure were investigated at room temperature. A modified Norde’s function combined with conventional forward I-V method was used to extract the parameters including barrier height (BH) and the series resistance. The barrier height and series resistance obtained from Norde’s function was compared with those from Cheung functions, and it was seen that there was a good agreement between series resistances from both methods. The C-V characteristics were performed at 10 kHz and 500 kHz frequencies, and C-f characteristics were performed 0.0 V, +0.4 V and −0.4 V.     

Reverse I-V characteristics in Au-GaAs Schottky diode in the presence of interfacial layer

The existence of an interfacial layer in an Au-GaAs Schottky diode may be revealed by measuring its I-V characteristics at very low reverse bias voltage. It is shown in this letter that a voltage dividing factor m can be used [see (2) of the text] to describe the effect of the interfacial layer on the I-V characteristics of the diode at low bias voltage.