金刚石场效应管的研究与展望

介绍了金刚石器件的发展现状与技术,对金刚石双极器件和金刚石场效应管进行了分析,同时讨论了该领域未来的研究趋向。     

RF performance of diamond MISFETs

A cutoff frequency (f_T) of 11 GHz is realized in the hydrogen-terminated surface channel diamond metal-insulator-semiconductor field-effect transistor (MISFET) with 0.7 μm gate length. This value is five times higher than that of 2 μm gate metal-semiconductor (MES) FETs and the maximum value in diamond FETs at present. Utilizing CaF₂ as an insulator in the MIS structure, the gate-source capacitance is reduced to half that of the diamond MESFET because of the gate insulator capacitance being in series to the surface-channel capacitance. This FET also exhibits the highest f _max of 18 GHz and 15 dB of power gain at 2 GHz. The high-frequency equivalent circuits of diamond MISFET are deduced from the S-parameters obtained from RF measurement     

Novel programmable high-speed analog transversal filter

A totally monolithic surface acoustic wave transversal filter has been demonstrated which utilizes an integrated multiplexed FET array to program the desired filter function. The device is based on ZnO on Si SAW technology with the FET array being fabricated using a standard NMOS processing schedule. Experimental results are presented which show the analog correlation of RF modulated waveforms (fo= 100 MHz) with various preprogrammed filter functions.     

High temperature device simulation and thermal characteristics of GaAs MESFETs on CVD diamond substrates

The temperature stability and high temperature characteristics of GaAs FETs on CVD diamond heat sinks were investigated by modeling the high-temperature electrical characteristics for GaAs MESFETs and by experimentally measuring the elevated-temperature performance. The bias region for the zero temperature coefficient (ZTC) was determined. The thermal characteristics were determined by infrared microscopy and the results were correlated with a finite element analysis calculation of the GaAs FET thermal distribution. The utilization of CVD diamond as a heat spreading substrate is shown to reduce the peak channel temperature by 30 percent when the FET is biased at the 1 dB compression point.     

Enhancement mode metal-semiconductor field effect transistors fromthin-film polycrystalline diamond

Polycrystalline CVD diamond films with a near surface hydrogenated layer have been used to form the first normally off enhancement mode MESFET structures from this material. A room temperature transconductance of 0.14 mS/mm has been measured, the highest yet reported for a transistor structure made from polycrystalline material. The devices fully turn off, display saturation and have a low gate leakage current. Al forms a near ideal Schottky barrier on this material (SBH ~0.98 eV, ideality <1.1) and was used as the gate metallization within the MESFET. Optimized forms of these structures would appear to offer a commercially viable route to high-performance diamond based electronic circuits     

Luminescence of Nanodiamond Driven by Atomic Functionalization: Towards Novel Detection Principles

High biocompatibility, variable size ranging from ≈5 nm, stable luminescence from its color centers, and simple carbon chemistry for biomolecule grafting make nanodiamond (ND) particles an attractive alternative to molecular dyes for drug‐delivery. A novel method is presented that can be used for remote monitoring of chemical processes in biological environments based on color changes from photoluminescent (PL) nitrogen‐vacancy (NV) centers in ND. The NV luminescence is driven chemically by alternating the surface chemical potential by interacting atoms and molecules with the diamond surface. Due to the small ND size, the changes of the surface chemical potential modify the electric field profile at the diamond surfaces (i.e., band bending) and intermingle with the electronic NV states. This leads to changes in NV^?/NV° PL ratio and allows construction of optical chemo‐biosensors operating in cells, with PL visible in classical confocal microscopes. This phenomenon is demonstrated on single crystal diamond containing engineered NV centers and on oxidized and hydrogenated ND in liquid physiological buffers for variously sized ND particles. Hydrogenation of NDs leads to quenching of luminescence related to negatively charged (NV^?) centers and as a result produces color shifts from NV^? (638 nm) to neutral NV° (575 nm) luminescence. How the reduction of diamond size increases the magnitude of the NV color shift phenomena is modeled.     

Current-voltage characteristics of thin film and bulk diamondtreated in hydrogen plasma

It is shown that the electrical properties of thin film and bulk diamond can be systematically altered by hydrogen plasma treatment under controlled conditions. The concentration of electrically active hydrogen introduced in diamond can be determined from the current-voltage characteristics of hydrogenated samples containing traps. Hydrogen passivation of deep traps in diamond is clearly demonstrated     

Diamond surface-channel FET structure with 200 V breakdown voltage

An enhancement mode diamond FET using a hydrogen-terminated surface as hole conductive channel has been fabricated with 200 V gate to drain breakdown voltage. At the 8.5-μm gate length the maximum drain current was 22 mA/mm. 90 mA/mm maximum drain current was obtained at a gate length of 3.0 μm. Scaling to below 1 μm gate length assuming undegraded breakdown conditions will result in a projected RF power handling capability above 6 W/mm     

面向微集成的金刚石NV色心与微波天线的一体化

针对金刚石氮空位(NV)色心量子传感器中微波天线体积大、无法与金刚石紧密接触造成天线与金刚石位置不固定、引起传感器灵敏度低的问题,设计了一种将微波天线集成到金刚石NV色心的一体化方法.采用导电性更强的金薄膜作为天线材料,通过高频结构模拟器(HFSS)仿真软件确定天线尺寸.利用微纳加工工艺和磁控溅射技术在金刚石NV色心表...     

Characterization of thin active layer on semi-insulating GaAs by mapping of FET array performance

A computer-aided FET performance measurement system was established to characterize a thin active layer formed on a semi-insulating GaAs substrate. By mapping FET array performances on a thin active layer, this system was applicable to substrate material quality evaluation and to a check of FET fabrication processes. It also gave the key information on FET threshold voltage scattering to the GaAs IC circuit designer. Most importantly, it was powerful in the characterization of thin active layers for which conventional methods, such as resistivity, Hall, or C-V measurements, were not effective because of the surface depletion layer into the thin active layer. It is demonstrated that dislocations in substrate crystal were clearly revealed to affect FET threshold scattering on the active layer formed by direct ion implantation on an LEC-grown semi-insulating substrate.     

Low-field low-frequency dispersion of transconductance in GaAsMESFETs with implications for other rate-dependent anomalies

A theory that emphasizes the role of surface states in the operation of GaAs MESFETs and that is intended to tie together hitherto unconnected anomalies in device behavior is presented. Such undesirable effects are consistent with the DC and microwave characteristics of the FET being modified by charge exchange with surface states. Generally speaking, these states are relatively slow, having characteristics frequencies of typically 1 kHz, but they nevertheless affect the microwave scattering parameters of the FET through the distortion they introduce to the shape of the depletion region in the transistor under given bias conditions. It is argued that the FET structure behaves as natural `probe' of surface states and so constitutes a useful analytic tool for studying states on a variety of unpassivated and passivated surfaces     

Enhancement of the steady state minority carrier lifetime in HgCdTe photodiode using ECR plasma hydrogenation

This paper reports the effects of electron cyclotron resonance (ECR)H₂ plasma hydrogenation on the characteristics of HgCdTe devices for the first time. We compared the characteristics of photodiodes and n-channel enhancement type field effect transistors (FETs) in the hydrogenated regions with those in the unhydrogenated regions on the same wafer. From the measurement of the photodiodes, it was found that the steady-state minority carrier diffusion length was increased from 19 to 28 urn by the hydrogenation. The surface mobility of the n-channel FET was about 5800 cm²Vs and was not varied by hydrogénation. From these facts, the steady-state minority carrier lifetime is increased about two times by the ECR H₂ plasma hydrogenation. We believe that the ECR hydrogenation can effectively reduce the surface trap-states which results in increasing the minority carrier lifetime and improving the characteristics of HgCdTe devices.     

单点金刚石车削技术的研究

介绍了单点金刚石车削原理,分析了单点金刚石车削技术中影响光学零件面形精度和粗糙度的重要技术因素,同时提出了相应的解决方案,并展望了单点金刚石车削技术在光学制造领域的应用前景.     

RF power performance evaluation of surface channel diamond MESFETs

We experimentally investigate the large-signal radio frequency performances of surface-channel p-type diamond MESFETs fabricated on hydrogenated polycrystalline diamond. The devices under examination have a coplanar layout with two gate fingers, total gate periphery of 100 μm; in DC they exhibit a hole accumulation behavior with threshold voltage V_t ≈ 0-0.5 V and maximum drain current density of 120 mA/mm. The best small-signal radio frequency performances (maximum cutoff or transition frequency f_T and oscillation frequency f_max) were obtained close to the threshold and were of the order of 6 and 15 GHz, respectively. The power radio frequency response was characterized by driving the devices in class A at an operating frequency of 2 GHz and identifying through the active load-pull technique the optimum load for maximum power added efficiency. A power gain in linearity of 8 dB and an output power of approximately 0.2 W/mm with 22% power added efficiency were obtained on the optimum load impedance at a bias point V_DS = −14 V, V_GS = −1 V. To the best of our knowledge, these are the first large signal measurements ever reported for surface MESFET on polycrystalline diamond, and show the potential of such technology for the development of microwave power devices.     

Planar monolithic integration of LED and FET devices on a conductive substrate

This paper describes results of a study on the monolithic integration of AlGaAs light-emitting diodes with GaAs field-effect transistors on a conductive p-GaAs substrate. Using a selective growth technique, a horizontal configuration is fabricated that allows separate optimization of the two types of devices and provides a quasi-planar surface. This approach is compatible with the standard GaAs integrated-circuit technology. By inserting an undoped layer and a p-n junction between the active layer of the FET and the substrate leakage currents below 500 µA for bias voltage up to 9 V are obtained for these insulation structures. The emitted light intensity of the LED, connected in series with the FET, exhibits a nearly linear dependence on the driving gate potential. Temperature or optical crosstalk effects were not observed. Fall and rise times around 20 ns were measured from the pulse response characteristics. This switching time is limited by the LED whereas the FET and isolation layers were found not to affect the switching behavior of the circuit in this time frame.     

Fabrication of Metal–Oxide–Diamond Field-Effect Transistors with Submicron-Sized Gate Length on Boron-Doped (111) H-Terminated Surfaces Using Electron Beam Evaporated SiO<Subscript>2</Subscript> and Al<Subscript>2</Subscript>O<Subscript>3</Subscript>

A H-terminated surface conductive layer of B-doped diamond on a (111) surface was used to fabricate a metal–oxide–semiconductor field-effect transistor (MOSFET) using an electron beam evaporated SiO₂ or Al₂O₃ gate insulator and a Cu-metal stacked gate. When the bulk carrier concentration was approximately 10¹⁵/cm³ and the B-doped diamond layer was 1.5 μm thick, the surface carrier mobility of the H-terminated surface on the (111) diamond before FET processing was 35 cm²/Vs and the surface carrier concentration was 1.5 × 10¹³/cm². For the SiO₂ gate (0.76 μm long and 50 μm wide), the maximum measured drain current at a gate voltage of −3.0 V was −75 mA/mm and the maximum transconductance was 24 mS/mm, and for the Al₂O₃ gate (0.64 μm long and 50 μm wide), these features were −86 mA/mm and 15 mS/mm, respectively. These values are among the highest reported direct-current (DC) characteristics for a diamond homoepitaxial (111) MOSFET.     

A GaAs MESFET Oscillator Quasi-Linear Design Method

A simplified quasi-linear method is proposed to design a GaAs MESFET oscillator. By expressing the generated power P/sub gen/ as a function of FET gate and drain RF voltages, it is possible to maximize P/sub gen/ under the limiting conditions on intrinsic FET terminal voltage amplitudes. The feedback circuit elements to realize a GaAs MESFET oscillator are derived. An X-band GaAs MESFET oscillator was designed by the quasi-linear method and was fabricated by using microwave integrated-circuit technology.     

固态微波电子学的新进展

固态微波电子学是现代电子学的重要分支之一,其基础材料已由第一代半导体Si和Ge、第二代半导体GaAs和InP,发展到第三代半导体GaN和SiC,石墨烯和金刚石等C基新材料正在进行探索性的研究,其加工工艺的尺寸也已进入纳米尺度,其工作频率已达到1 THz,应用的频率可覆盖微波毫米波到太赫兹.目前固态微波电子学呈多代半导体材料和器件共同发展的格局.综述了具有代表性的1 1类固态器件(RF CMOS,SiGe BiCMOS,RF LDMOS,RF MEMS,GaAs PHEMT,GaAs MHEMT,InP HEMT,InP HBT,GaN/SiC HEMT,GFET和金刚石FET)近几年的最新研究进展,详细介绍了有关固态微波电子学的应用需求、技术特点、设计拓扑、关键技术突破和测试结果,分析了当前固态微波电子学总的发展趋势和11类固态微波器件的发展特点和定位.最后介绍了采用3D异构集成技术的射频微系统的最新进展,指出射频微系统是发展下一代射频系统的关键技术.     

Low dissipation current GaAs prescaler IC

A 1 GHz variable modulus freqency divider with very low dissipation current has been developed. Using a high-transconductance (200?250 mS/mm) FET by Pt burying technology and series gating source-coupled FET logic, the dissipation current of the fabricated IC was reduced to 3.2 mA at 1 GHz operation.     

微波功率晶体管的发展与分析

本文阐述了国内外硅双极微波功率晶体管和砷化镓微波功率场效应晶体管的发展历史和现状,并分析了微波功率晶体管的发展特点。介绍了HBT,HFET,MISFET,金刚石、SiC电子器件,真空微电子器件等用于或将用于微波、毫米波功率领域中的情况。提出了发展微波功率晶体管的几点想法。