A review of the etched terminal structure of a 4H-SiC PiN diode

The comparison of domestic and foreign studies has been utilized to extensively employ junction termination extension(JTE)structures for power devices.However,achieving a gradual doping concentration change in the lateral direction is difficult for SiC devices since the diffusion constants of the implanted aluminum ions in SiC are much less than silicon.Many previously reported studies adopted many new structures to solve this problem.Additionally,the JTE structure is strongly sensitive to the ion implantation dose.Thus,GA-JTE,double-zone etched JTE structures,and SM-JTE with modulation spacing were reported to overcome the above shortcomings of the JTE structure and effectively increase the breakdown voltage.They provided a theoretical basis for fabricating terminal structures of 4H-SiC PiN diodes.This paper summarized the effects of different terminal structures on the electrical properties of SiC devices at home and abroad.Presently,the continuous development and breakthrough of terminal technology have significantly improved the breakdown voltage and terminal efficiency of 4H-SiC PiN power diodes.

GaAs PIN Diodes for X-Band Low Loss and High Isolation Switches

GaAs PIN diodes optimized for X-band low loss and high isolation switch application are presented. The impact of diode physical characteristics and electrical parameters on switch performance is discussed. A new structure for GaAs PIN diodes is proposed and the fabrication process is described. GaAs PIN diodes with an on-state resistance of 〈2. 2Ω and off-state capacitance -〈20fF in the range of 100MHz to 12.1GHz are obtained.

A Novel Equivalent Circuit Model of GaAs PIN Diodes

A novel equivalent circuit model for a GaAs PIN diode is presented based on physical analysis. The diode is divided into three parts： the p^＋ n^- junction, the i-layer, and the n^- n^＋ junction, which are modeled separately. The entire model is then formed by combining the three sub-models. In this way, the model＇s accuracy is greatly enhanced. Furthermore, the corresponding parameter extraction method is easy, requiring no rigorous experiment or measurement. To validate this newly proposed model,fifteen groups of diodes are fabricated. Measurement shows that the model exactly represents behavior of GaAs PIN diodes under both forward and reversely biased conditions.

A C-Band Monolithic GaAs PIN Diode SPST Switch

A monolithic single pole single throw （SPST） switch is developed with GaAs PIN diode technology from IMECAS. A novel small signal model of a GaAs PIN diode is developed for circuit simulation. The switch features an on-state insertion loss of less than 1.6dB and a return loss of greater than 10dB while maintaining an off-state isolation of greater than 23dB from 5.5 to 7. 5GHz. The measured 1dB power gain compression point is about 20dBm.

Electron Temperature Measurement Using PIN Diodes as Detectors to Record the X-ray Pulses from a Low-Energy Mather-Type Plasma Focus

In the experiment to determine the plasma electron temperature, a modifiedmultichannel PIN diodes assembly is used as detectors to record the X-ray pulses from a low-energyMather-type plasma focus device energized by a 32μF, 15 kV (3.6kJ) single capacitor, with deuteriumas a filling gas. The ratio of the integrated bremsstrahlung emission transmitting through foils tothe total incident flux as a function of foil thickness at various temperatures is obtained forfoil absorbers of material. Using 3 μm, 6 μm, 9 μm,12 μm,15 μm and 18 μm thick aluminiumabsorbers, the transmitted X-ray flux is detected. By comparing the experimental and theoreticalcurves through a computer program, the plasma electron temperature is determined. Results show thatthe deuterium focus plasma electron temperature is about 800 eV.

A betavoltaic microbattery based on PIN diodes

A betavohaic Microbattery was studied. The diode was composed of a PIN structure with an active area of 10 mm × 10 mm to collect the charge from a 10mCi Ni-63 source. An open circuit voltage of 0. 16 V and a short circuit current density of 67.6 nA/cm2 were measured. An efficiency （η） of 1.44% was obtained. The performance of device was limited by high series resistance, edge recombination and attenuation of electron in PIN diodes. It is expected to be improved by optimizing the design and using more suitable radioisotope.

Design of double-layer active frequency-selective surface with PIN diodes for stealth radome

An experimental double-layer active frequency-selective surface（AFSS） for stealth radome is proposed. The AFSS is a planar structure which is composed of a fixed frequency-selective surface（FSS）, a PIN diodes array, and a DC bias network. The AFSS elements incorporating switchable PIN diodes are discussed. By means of controlling the DC bias network, it is possible to switch the frequency response for reflecting and transmitting. Measured and simulated data validate that when the incidence angle varies from 0°to 30° the AFSS produces more than-11.5 dB isolation across6–18 GHz when forward biased. The insertion loss（IL） is less than 0.5 dB across 10–11 GHz when reverse biased.

An Analysis of the Equivalent Resistance of PIN Diodes at Microwave Frequencies

The forward bias equivalent resistance of PIN diodes, an important parameter in applications, is usually measured at lower frequencies. But in fact, due to skin effect the effective conduction area of the region I of a PIN diode decreases as the frequency increases. In this paper, the affection of skin effect to forward bias equivalent resistance is considered and an analytic expression of the equivalent resistance of the region I is presented. In result, the forward bias resistance of a PIN diode at microwave frequencies is much higher than that at DC and low frequencies. It is necessary, therefore, to consider the skin effect of PIN diodes in high frequency applications.

Novel layout design of 4H-SiC merged PiN Schottky diodes leading to improved surge robustness

A method to improve the surge current capability of silicon carbide(SiC)merged PiN Schottky(MPS)diodes is presented and investigated via three-dimensional electro-thermal simulations.When compared with a conventional MPS diode,the proposed structure has a more uniform current distribution during bipolar conduction due to the help of the continuous P+surface,which can avoid the formation of local hotspots during the surge process.The Silvaco simulation results show that the proposed structure has a 20.29%higher surge capability and a 15.06%higher surge energy compared with a conventional MPS diode.The bipolar on-state voltage of the proposed structure is 4.69 V,which is 56.29%lower than that of a conventional MPS diode,enabling the device to enter the bipolar mode earlier during the surge process.Furthermore,the proposed structure can suppress the occurrence of‘snapback'phenomena when switching from the unipolar to the bipolar operation mode.In addition,an analysis of the surge process of MPS diodes is carried out in detail.

An 8～20GHz Monolithic SPDT GaAs pin Diode Switch

Monolithic GaAs pin diode single pole double throw （SPDT） switches based on the fabrication technology of IMECAS are designed,fabricated,and tested. These SPDT switches achieve an insertion loss of 1.5dB,isolation of 32dB, and input and output return losses over 10dB from 8 to 20GHz. The switch design uses 2.5μm thick I-region GaAs pin diodes and a series-shunt-shunt switch topology in each arm. These performance characteristics are measured at a normal bias setting of 1.3V,which corresponds to 7mA of series diode bias current.

Motion of current filaments in avalanching PIN diodes

The motion of current filaments in avalanching PIN diodes has been investigated in this paper by 2D transient numerical simulations. The simulation results show that the filament can move along the length of the PIN diode back and forth when the self-heating effect is considered. The voltage waveform varies periodically due to the motion of the filament. The filament motion is driven by the temperature gradient in the filament due to the negative temperature dependence of the impact ionization rates. Contrary to the traditional understanding that current filamentation is a potential cause of thermal destruction, it is shown in this paper that the thermally-driven motion of current filaments leads to the homogenization of temperature in the diode and is expected to have a positive influence on the failure threshold of the PIN diode.

1.4 kV 4H-SiC PiN diode with a robust non-uniform floating guard ring termination

This paper presents the design and fabrication of an effective, robust and process-tolerant floating guard ring termination on high voltage 4H-SiC PiN diodes. Different design factors were studied by numerical simulations and evaluated by device fabrication and measurement. The device fabrication was based on a 12 μm thick drift layer with an N-type doping concentration of 8 × 10^15 cm^-3. P^＋ regions in the termination structure and anode layer were formed by multiple aluminum implantations. The fabricated devices present a highest breakdown voltage of 1.4 kV, which is higher than the simulated value. For the fabricated 15 diodes in one chip, all of them exceeded the breakdown voltage of 1 kV and six of them reached the desired breakdown value of 1.2 kV.

High-voltage 4H-SiC PiN diodes with the etched implant junction termination extension

This paper presents the design and fabrication of an etched implant junction termination extension（JTE）for high-voltage 4H-SiC PiN diodes. Unlike the conventional JTE structure, the proposed structure utilizes multiple etching steps to achieve the optimum JTE concentration range. The simulation results show that the etched implant JTE method can improve the blocking voltage of SiC PiN diodes and also provides broad process latitude for parameter variations, such as implantation dose and activation annealing condition. The fabricated SiC PiN diodes with the etched implant JTE exhibit a highest blocking voltage of 4.5 kV and the forward on-state voltage of 4.6 V at room temperature. These results are of interest for understanding the etched implant method in the fabrication of high-voltage power devices.

Characteristics and analysis of 4H-SiC PiN diodes with a carbon-implanted drift layer

The characteristics of 4H-SiC PiN diodes with a carbon-implanted drift layer was investigated and the reason of characteristics improvement was analyzed. The forward voltage drops of the diodes with carbonimplanted drift layer were around 3.3 V, which is lower than that of devices without carbon implantation, the specific-on resistance was decreased from 9.35 to 4.38 mΩcm^2 at 100 A/cm^2, and the reverse leakage current was also decreased. The influence of carbon incorporation in the Si C crystalline grids was studied by using deep-level transient spectroscopy（DLTS）. The DLTS spectra revealed that the Z_（1/2） traps, which were regarded as the main lifetime limiting defects, were dramatically reduced. It is proposed that the reduction of Z_（1/2） traps can achieve longer carrier lifetime in the drift layer, which is beneficial to the performance of bipolar devices.

Temperature-variable high-frequency dynamic modeling of PIN diode

The PIN diode model for high frequency dynamic transient characteristic simulation is important in conducted EMI analysis. The model should take junction temperature into consideration since equipment usually works at a wide range of temperature. In this paper, a temperature-variable high frequency dynamic model for the PIN diode is built, which is based on the Laplace-transform analytical model at constant temperature. The relationship between model parameters and temperature is expressed as temperature functions by analyzing the physical principle of these parameters. A fast recovery power diode MUR1560 is chosen as the test sample and its dynamic performance is tested under inductive load by a temperature chamber experiment, which is used for model parameter extraction and model verification. Results show that the model proposed in this paper is accurate for reverse recovery simulation with relatively small errors at the temperature range from 25 to 120 ℃.

Simulation study of a mixed terminal structure for 4H-SiC merged PiN/Schottky diode

In this paper, a mixed terminal structure for the 4H-SiC merged PiN/Schottky diode （MPS） is investigated, which is a combination of a field plate, a junction termination extension and floating limiting rings. Optimization is performed on the terminal structure by using the ISE-TCAD. Further analysis shows that this structure can greatly reduce the sensitivity of the breakdown voltage to the doping concentration and can effectively suppress the effect of the interface charge compared with the structure of the junction termination extension. At the same time, the 4H-SiC MPS with this termination structure can reach a high and stable breakdown voltage.

Effects of Oxygen Concentration in Monocrystalline Silicon on Reverse Leakage Current of PIN Rectifier Diodes

The effects of initial oxygen concentration on the reverse leakage current of PIN rectifier diodes were studied.We fabricated the PIN rectifier diodes with different initial oxygen concentrations,and analyzed the electrical properties,anisotropic preferred etching by means of optical microscopy,Fourier transform infrared spectroscopy and transmission electron microscopy.It is pointed out that the reverse leakage current increases exponentially with the increasing initial oxygen concentration.Furtherly,we researched and analyzed the mechanism of the effects of initial oxygen concentration on the reverse leakage current of PIN rectifier diode.It is shown that the oxygen precipitations present in an "S" curve with increasing initial oxygen concentration after high temperature diffusion.The main reason is that the nucleation and growth of oxygen precipitation at high temperature induce bulk oxidation-induced defects (B-OSF),which are mainly dislocations,and a small amount of rod stacking faults.The density of B-OSF increases with the increasing initial oxygen concentration.The existence of B-OSF has great effects on the reverse leakage current of PIN rectifier diode.

Optimized online filter stack spectrometer for ultrashort X-ray pulses

Currently,with the advent of high-repetition-rate laser-plasma experiments,the demand for online diagnosis for the X-ray spectrum is increasing because the laser-plasma-generated X-ray spectrum is very important for characterizing electron dynamics and applications.In this study,scintillators and silicon PIN(P-type–intrinsic-N-type semiconductor)diodes were used to construct a wideband online filter stack spectrometer.The X-ray sensor and filter arrangement was optimized using a genetic algorithm to minimize the condition number of the response matrix.Consequently,the unfolding error was significantly reduced based on numerical experiments.The detector responses were quantitatively calibrated by irradiating the scintillator and PIN diode with various nuclides and comparing the measuredγ-ray peaks.A prototype 15-channel spectrometer was developed by integrating an X-ray detector with front-and back-end electronics.The prototype spectrometer could record X-ray pulse signals at a repetition rate of 1 kHz.Furthermore,an optimized spectrometer was employed to record the real-time spectra of laser-driven bremsstrahlung sources.This optimized spectrometer offers a compact solution for spectrum diagnostics of ultrashort X-ray pulses,exhibiting improved accuracy in terms of spectrum measurements and repetition rates,and could be widely used in next-generation high-repetition-rate high-power laser facilities.

An ultrahigh-voltage 4H-SiC merged Pi N Schottky diode with three-dimensional p-type buried layers

In the modern society,there is a strong demand for semiconductor chips,and the 4H polytype silicon carbide(4H-SiC)power device is a promising candidate for the next generation semiconductor chip,which can be used in various power electronic systems.In order to improve the performance of the 4H-SiC power device,a novel ultrahigh-voltage(UHV)4H-SiC merged p-type/intrinsic/n-type(PiN)Schottky(MPS)diode with three-dimensional(3D)p-type buried layers(PBL)(3D-PBL MPS)is proposed and investigated by numerical simulation.The static forward conduction characteristics of the 3D-PBL MPS are similar to those of the conventional 4H-SiC MPS diode without the PBL(PBL-free MPS).However,when the 3D-PBL MPS is in the reverse blocking state,the 3D PBL can transfer the peak electric field(E_(peak))into a deeper position in the body of the epitaxial layer,and enhance the ability of the device to shield the high electric field at the Schottky contact interface(E_(S)),so that the reverse leakage current of the 3D-PBL MPS at 10 kV is only 0.002%of that of the PBL-free MPS.Meanwhile,the novel 3D-PBL MPS has overcome the disadvantage in the 4H-SiC MPS diode with the two-dimensional PBL(2D-PBL MPS),and the forward conduction characteristic of the 3D-PBL MPS will not get degenerated after the device converts from the reverse blocking state to the forward conduction state because of the special depletion layer variation mechanism depending on the 3D PBL.All the simulation results show that the novel UHV 3D-PBL MPS has excellent device performance.

Cactus-Shaped Frequency Reconfigurable Antenna for Sub 10 GHz Wireless Applications

This paper presents,a novel cactus shaped frequency reconfigurable antenna for sub 10 GHz wireless applications.PIN diode is utilized as an electrical switch to achieve reconfigurability,enabling operation in four different frequency ranges.In the switch ON state mode,the antenna supports 2177-3431 and 6301-8467 MHz ranges.Alternatively,the antenna resonates within 2329-3431 and 4951-6718 MHz while in the OFF state mode.Radiation efficiency values,ranging from 68%to 84%,and gain values,ranging from 1.6 to 4 dB,in the operating frequency bands.the proposed antenna satisfy the practical requirements and expectations.The overall planner dimensions of the proposed antenna model is 40×21 mm^(2).Moreover,the measurement results from the prototype support the simulation results.Based on the frequency ranges supported by the antenna,it can be used for multiple wireless standards and services,including Worldwide interoperability and Microwave Access(WiMAX),Wireless Fidelity(Wi-Fi),Bluetooth,Long Term Evolution(LTE)and satellite communications.This increases its applicability for use in mobile terminals.