New High-Speed a-Si/c-Si- and a-SiC/c-Si-Based Switches (original) (raw)
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New a-Si/c-Si and a-SiC/c-Si based optically controlled switching devices
Semiconductor Science and Technology, 1995
The fabrication and characteristics of Al/a-Sijcsi(p)/GSi(n+)/Al and Ai/aSiC/c-Si(p)/c-Si(n')/Al switches are presented. Both switches use a non-hydrogenated amorphous thin film. The devices can be optically controlled, and exhibit forward breakover voltages (VeF) of 120-160 V. Their behaviour resembles that of a thyristor. A simple model for the device operation is also presented and discussed for the first time.
Journal of Semiconductors, 2017
A parametric study for a series of technological and geometrical parameters affecting rise time of Al/a-SiC/c-Si (p)/c-Si (n+)/Al thyristor-like switches, is presented here for the first time, using two-dimensional simulation techniques.By varying anode current values in simulation procedure we achieved very good agreement between simulation and experimental results for the rising time characteristics of the switch.A series of factors affecting the rising time of the switches are studied here.Two factors among all others studied here, exerting most significant influence, of more than one order of magnitude on the rising time, are a-SiC and c-Si (p) region widths, validating our earlier presented model for device operation.The above widths can be easily varied on device manufacture procedure.We also successfully simulated the rising time characteristics of our earlier presented simulated improved switch, with forward breakover voltage VBF=11 V and forward voltage drop VF=9.5 V at the ON state, exhibiting an ultra low rise time value of less than 10 ps, which in conjunction with its high anode current density values of 12 A/mm2 and also cheap and easy fabrication techniques, makes this switch appropriate for ESD protection as well as RF MEMS and NEMS applications.
Microelectronics Journal, 1998
The reversible effect of various factors, such as temperature, light intensity and potential applied to a gate electrode, on the electrical characteristics of new high-speed a-Si/c-Siand a-SiC/c-Si-based switches are, for the first time, presented and discussed in this paper. The irreversible effect of the width of amorphous film on the electrical characteristics of these switches is also studied. The values of forward breakover voltage (VBF), forward voltage drop (VF) and holding current (Ih) of these thyristor-like switches may be either reversibly or irreversibly controlled by varying the above factors, thus controlling the device operation.
6H-SiC photoconductive switches triggered at below bandgap wavelengths
IEEE Transactions on Dielectrics and Electrical Insulation, 2007
Semi-insulating silicon carbide (SiC) is an attractive material for application as high voltage, photoconductive semiconductor switches (PCSS) due to its large bandgap, high critical electric field strength, high electron saturation velocity and high thermal conductivity. The critical field strength of 300 MV/m for 6H-SiC makes it particularly attractive for compact, high voltage, fast switching applications. To realize the benefits of the high bulk electric field strength of SiC and diffuse switch current, carriers must be excited throughout the bulk of the photo switch. Photoconducting switches with opposing electrodes were fabricated on "a" plane, vanadium compensated, semiinsulating, 6H-SiC substrates. The PCSS devices were switched by optically exciting deep extrinsic levels lying within the 6H-SiC bandgap. The SiC photoswitches were tested up to a bias voltage of 11000 V with a corresponding peak current of 150 A. The 6H-SiC substrates withstood average electric fields up to 27 MV/m. Minimum PCCS dynamic resistances of 2 and 10 Ω were obtained with 13 mJ optical pulses at 532 and 1064 nm wavelengths, respectively.
2015
The electrical characteristics of the Al/a-SiC/c-Si(p)/c-Si(n +)/Al switches were successfully simulated here for the first time. Forward breakover voltage V BF , forward voltage drop V F and anode current simulated values of the device showed very good agreement with the experimental results. Electric field and impact generation rate across the switches are also simulated for different anode current conditions extending to second breakdown region of the device, showing a shifting of the phenomena caused by electric field and impact generation rate, from c-Si(p) region to a-SiC film as anode voltage values increase from V BF up to second breakdown region of the device. A both simulation and experimental based model describing the device behavior, is also presented here. Two critical facts leading to switching transition are proved to be at first a-SiC/c-Si(p) heterojunction breakdown dominated by impact generation rate and second subsequent trap filling in the amorphous film. Al/a-SiC/c-Si(p +)/c-Si(p)/c-Si(n +)/Al switches with reduced V BF and V F values, were also fabricated and successfully simulated here, enhancing the validity of our simulation procedure and making the switches candidates for ESD protection devices, also due to their advantages of high anode current value density of 5 A/mm 2 before reaching second breakdown conditions in conjunction with cheap and easy fabrication procedure mainly due to r.f. sputtering technique used for a-SiC film fabrication.
Experimental and Modeling Study of Optically Triggered SiC 1000 V p–i–n Diode Switches
Applied Physics Express, 2012
SiC photoconductive switches combine the advantages of both SiC power electronics for high power and high efficiency at high temperature, and optically controlled devices for fast switching, enhanced reliability, and electromagnetic interference (EMI) immunity. In this work, SiC optically triggered diode (OTD) was designed and fabricated. The diode successfully switched 1000 V when illuminated by a single laser pulse of 337.1 nm wavelength and 1.2 mJ optical energy. A physical device model was validated by test results, from which the on-state resistance and peak photocurrent under different bias voltages and optical energies were calculated, and the potential of these optical diodes was further explored.
Silicon carbide photoconductive switches
1994
The optoelectronic properties of p-type 6-H silicon carbide (6H-SiC) have been investigated in an experiment that used lateral and vertical photoconductive (PC) switches. Both photovoltaic and photoconductive effects are reported, which were observed on switches using both geometries and measured at several wavelengths near the 6H-SiC absorption edge. PC techniques were employed to measure the surface and bulk carrier lifetimes of 40 and 200 ns, respectively. The switches displayed a high-speed photovoltaic response to picosecond laser excitations in the UV and visible spectral regions. In particular, efficient subnanosecond optical absorption processes were observed in the visible region. The photovoltage was measured as a function of both laser wavelength (and hence absorption depth) and laser beam position within the switching gap. The switch response to picosecond laser pulses in the UV, violet, green, and red spectral regions was shown to have subnanosecond photovoltaic response times. Finally, since the optical absorption coefficient had not been well established for device-grade 6H-SiC, the optical absorption coefficient near the 6H-SiC bandgap energy (Eg) was also measured, and the bandgap was determined to be approximately 3.1 eV.
Optical Processing Devices for Optical Communications: Multilayered a-SiC:H Architectures
MRS Proceedings, 2009
In this paper three multilayered architectures based on a-SiC:H with voltage controlled spectral selectivity in the visible spectrum range are analyzed. Multiple simultaneous modulated communication channels (red, green and blue or their polychromatic mixtures) were transmitted together at different frequencies. The combined optical signal was analyzed by reading out the photocurrent signal generated by the devices, under different applied voltages. Results show that the multiplexed signal depends on the device architecture and is balanced by the wavelength and transmission speed of each input channel, keeping the memory of the incoming optical carriers. In the single graded p-i'i-n configuration the device acts mainly as an optical switch while in two stacked p-i'-n-(ITO)-p-i-n configurations, the input channels are selectively tuned by shifting between forward and reverse bias. An electrical model, supported by a numerical simulation gives insight into the device operation.
Optical Switch Performance for Electronic Applications
Recent Trends in Intensive Computing, 2021
In this paper, various optically controlled switch performances are studied and analysed. Different types of optically controlled materials are considered in this paper to control the electrical frequency with a modified and simpler structure. Roger and Fr-4 materials are used as substrate material for the basic system design with the dielectric constant of 3.0 and 4.4 respectively. Materials like silicon, germanium, graphene, and polymers are considered for analysis in the proposed system and the semiconductor metals are etched in the middle of the copper strip. The thickness of the copper is 0.008 mm with the standard conductivity of 5.814e7 S/m and the length and width of the copper strip are 2.54x2.54mm. A Copper strip is printed on the substrate to test the performance of the switches. The operating frequency of the given optical signal of silicon is around 1GHz to 25GHz, graphene is around 1GHz to 30GHz, germanium is around1GHz to 30GHz and polymer is around 1GHz to25GHz. The ...
A High-powered Optoelectronic Switch with Picosecond Risetime
1980
A switch element has been developed so that a kilovolt step voltage should be supplied to a 50Ω transmission line with a subnanosecond rise time. The element is of silicon substrate with high purity and a pair of electrodes is attached by the evaporation process. The switch action is performed by the photoconductivity produced by the laser light pulse. This paper deals with a preliminary analysis, manufacturing processes and experimental results of the optoelectronic switch. A performance of 320V output with less than 4 ns risetime was obtained with sufficient persistence for more than 2×10(5) pulse shots. This switch was successfully applied to an optical waveform monitor for laser light pulses giving a resolution less than 2 ns