GaAs TUNNETT diodes on diamond heat sinks for 100 GHz and above

2012

Appl Nanosci

In this paper the potentiality of impact avalanche transit time (IMPATT) devices based on different semiconductor materials such as GaAs, Si, InP, 4H-SiC and Wurtzite-GaN (Wz-GaN) has been explored for operation at terahertz frequencies. Drift-diffusion model is used to design double-drift region (DDR) IMPATTs based on different materials at millimeter-wave (mm-wave) and terahertz (THz) frequencies. The performance limitations of these devices are studied from the avalanche response times at different mm-wave and THz frequencies. Results show that the upper cut-off frequency limits of GaAs and Si DDR IMPATTs are 220 GHz and 0.5 THz, respectively, whereas the same for InP and 4H-SiC DDR IMPATTs is 1.0 THz. Wz-GaN DDR IMPATTs are found to be excellent candidate for generation of RF power at THz frequencies of the order of 5.0 THz with appreciable DC to RF conversion efficiency. Further, it is observed that up to 1.0 THz, 4H-SiC DDR IMPATTs excel Wz-GaN DDR IMPATTs as regards their RF power outputs. Thus, the wide bandgap semiconductors such as Wz-GaN and 4H-SiC are highly suitable materials for DDR IMPATTs at both mm-wave and THz frequency ranges.

Section: Introductionmentioning

confidence: 99%

Prospects of IMPATT devices based on wide bandgap semiconductors as potential terahertz sources

Acharyya

2012

Appl Nanosci

Journal of Applied Physics

“…The TD is a typical p ϩ n -type diode. [6][7][8] ͑2͒ Electron injection into a transit space of the PD is realized by electron tunneling through a moderately high square heterobarrier. It takes place in moderately strong electric fields (Eр10 5 V/cm).…”

Section: ͑1͒mentioning

confidence: 99%

“…In the TD, all the regions including the transit space are GaAs grown with low-lying electron L and X valleys. Therefore, in a relatively short transit space of the TD with lϷ300 nm, [6][7][8] there is diffusive electron transport with a drift velocity ϳ(1Ϫ2)ϫ10 7 cm/s. a͒ Author to whom correspondence should be addressed.…”

Section: ͑1͒mentioning

confidence: 99%

Ballistic and quasiballistic tunnel transit time oscillators for the terahertz range: Linear admittance

Gribnikov

Vagidov

Mitin

et al. 2003

We have considered interactions between ballistic ͑or quasiballistic͒ electrons accelerated by a dc electric field in an undoped transit space ͑T space͒ and a small ultrahigh frequency ac electric field and have calculated the linear admittance of the T space. Electrons in the T space have a conventional, nonparabolic dispersion relation. After consideration of the simplest specific case when the current is limited by the space charge of the emitted electrons, we turned to an actual case when the current is limited by a heterostructural tunnel barrier ͑B barrier͒ separating the heavily doped cathode contact and the T space. We assumed that the B barrier is much thinner than the T space and both dc and ac voltages drop mainly across the T space. The emission tunnel current through the B barrier is determined by the electric field E(0) in the T space at the boundary B barrier/T space. The more substantial is, the tunnel current limitation the higher the electric field E(0) becomes. We have shown that for a space-charge limited current the change from parabolic dispersion to the nonparabolic branch induces narrowing and closing of the frequency windows of transit-time negative conductance starting with the lowest-frequency windows. These narrowing and closing frequency windows become effective only for very high voltages U across the T space: UӷmV S 2 /2e, where m is the effective mass for the parabolic branch and V S is the saturated velocity for the nonparabolic branch. For moderate voltages U, the effects of nonparabolicity are not very substantial. The tunnel current limitation decreases the space-charge effects in the T space and diminishes the role of the detailed electron dispersion relation. As a result, restoration of the frequency windows of transit-time negative conductance and an increase in the value of this negative conductance occur. The implementation of the considered tunnel injection transit time oscillator diode promises to lead to efficient and powerful sources of terahertz range radiation.

“…Mixed tunneling avalanche transit time (MITATT) device is an important member of avalanche transit time (ATT) device family operating at higher millimeter-wave frequencies [11][12][13][14][15][16][17][18][19][20][21][22][23]. In 1958 W. T. Read [11] in his very early paper predicted that band-to-band tunneling phenomenon might limit the DC-to-RF conversion efficiency of the IMPATT diodes at high frequencies.…”

Section: Introductionmentioning

confidence: 99%

“…Elta [20] and Kane [21] showed that the performance of IMPATT devices deteriorates due to tunneling-induced phase distortion. Eisele and Haddad [22] also carried out experimental work on TUNNETT mode operation of IMPATT diodes grown on diamond heat sink. They reported highest RF conversion efficiency of TUNNETT devices.…”

Section: Introductionmentioning

confidence: 99%

Noise Performance of Heterojunction DDR MITATT Devices Based on at W-Band

Acharyya

Active and Passive Electronic Components

2013

Noise performance of different structures of anisotype heterojunction double-drift region (DDR) mixed tunneling and avalanche transit time (MITATT) devices has been studied. The devices are designed for operation at millimeter-wave W-band frequencies. A simulation model has been developed to study the noise spectral density and noise measure of the device. Two different mole fractions and of Ge and corresponding four types of device structure are considered for the simulation. The results show that the -Si heterojunction DDR structure of MITATT device excels all other structures as regards noise spectral density ( sec) and noise measure (33.09 dB) as well as millimeter-wave properties such as DC-to-RF conversion efficiency (20.15%) and CW power output (773.29 mW).