The terahertz (THz) technology has found applications ranging from astronomical science and earth observation to compact radars, non-destructive testing, chemical analysis, explosive detection, ...moisture content determination, coating thickness control, film uniformity determination, structural integrity testing wireless covert communications, medical applications (including skin cancer detection), imaging, and concealed weapons detection. Beyond 5G Wi-Fi and Internet of Things (IoT) are the expected killer applications of the THz technology. Plasmonic TeraFETs such as Si CMOS with feature sizes down to 3 nm could enable a dramatic expansion of all these applications. At the FET channel sizes below 100 nm, the physics of the electron transport changes from the collision dominated to the ballistic or quasi-ballistic transport. In the ballistic regime, the electron inertia and the waves of the electron density (plasma waves) determine the high frequency response that extends into the THz range of frequencies. The rectification and instabilities of the plasma waves support a new generation of THz and sub-THz plasmonic devices. The plasmonic electronics technology has a potential become a dominant THz electronics sensing technology when the plasmonic THz sources join the compact, efficient, and fast plasmonic TeraFET THz detectors already demonstrated and being commercialized.
We develop the device models for the far-infrared interband photodetectors (IPs) with the graphene-layer (GL) sensitive elements and the black Phosphorus (b-P) or black-Arsenic (b-As) barrier layers ...(BLs). These far-infrared GL/BL-based IPs (GBIPs) can operate at the photon energies
smaller than the energy gap, Δ
, of the b-P or b-As or their compounds, namely, at
≲2
/3 corresponding to the wavelength range
≳(6-12)
m. The GBIP operation spectrum can be shifted to the terahertz range by increasing the bias voltage. The BLs made of the compounds b-As
B
with different x, enable the GBIPs with desirable spectral characteristics. The GL doping level substantially affects the GBIP characteristics and is important for their optimization. A remarkable feature of the GBIPs under consideration is a substantial (over an order of magnitude) lowering of the dark current due to a partial suppression of the dark-current gain accompanied by a fairly high photoconductive gain. Due to a large absorption coefficient and photoconductive gain, the GBIPs can exhibit large values of the internal responsivity and dark-current-limited detectivity exceeding those of the quantum-well and quantum-dot IPs using the intersubband transitions. The GBIPs with the b-P and b-As BLs can operate at longer radiation wavelengths than the infrared GL-based IPs comprising the BLs made of other van der Waals materials and can also compete with all kinds of the far-infrared photodetectors.
p-Diamond, Si, GaN, and InGaAs TeraFETs Zhang, Yuhui; Shur, Michael S.
IEEE transactions on electron devices,
11/2020, Letnik:
67, Številka:
11
Journal Article
Recenzirano
Odprti dostop
p-Diamond field-effect transistors (FETs) featuring large effective mass, long momentum relaxation time, and high carrier mobility are a superb candidate for plasmonic terahertz (THz) applications. ...Previous studies have shown that p-diamond plasmonic THz FETs (TeraFETs) could operate in plasmonic resonant mode at a low-frequency window of 200 to ~600 GHz, thus showing promising potential for beyond 5G sub-THz applications. In this work, we explore the advantages of p-diamond transistors over n-diamond, Si, GaN, and InGaAs TeraFETs and estimate the minimum mobility required for the resonant plasmons. Our numerical simulation shows that the p-diamond TeraFET has a relatively low minimum resonant mobility, and thus could enable resonant detection. The diamond response characteristics can be adjusted by changing operating temperature. A decrease of temperature from 300 to 77 K improves the detection performance of TeraFETs. At both room temperature and 77 K, the p-diamond TeraFET presents a high detection sensitivity in a large dynamic range. When the channel length is reduced to 20 nm, the p-diamond TeraFET exhibits the highest dc response among all types of TeraFETs in a large frequency window.
Deep-Ultraviolet Light-Emitting Diodes Shur, M.S.; Gaska, R.
IEEE transactions on electron devices,
2010-Jan., 2010-01-00, 20100101, Letnik:
57, Številka:
1
Journal Article
Recenzirano
Compact solid-state deep-ultraviolet (DUV) light-emitting diodes (LEDs) go far beyond replacing conventional DUV sources such as mercury lamps. DUV LEDs enable new applications for air, water, and ...surface sterilization and decontamination, bioagent detection and identification, UV curing, and biomedical and analytical instrumentation. We review materials growth, device physics, design, fabrication, and performance of DUV LEDs with wavelength ranging from 210 to 365 nm, describe prototype systems for water purification and sterilization, and discuss other emerging applications and systems using DUV LEDs.
Ever increasing demands of data traffic makes the transition to 6G communications in the 300 GHz band inevitable. Short-channel field-effect transistors (FETs) have demonstrated excellent potential ...for detection and generation of terahertz (THz) and sub-THz radiation. Such transistors (often referred to as TeraFETs) include short-channel silicon complementary metal oxide (CMOS). The ballistic and quasi-ballistic electron transport in the TeraFET channels determine the TeraFET response at the sub-THz and THz frequencies. TeraFET arrays could form plasmonic crystals with nanoscale unit cells smaller or comparable to the electron mean free path but with the overall dimensions comparable with the radiation wavelength. Such plasmonic crystals have a potential of supporting the transition to 6G communications. The oscillations of the electron density (plasma waves) in the FET channels determine the phase relations between the unit cells of a FET plasmonic crystal. Excited by the impinging radiation and rectified by the device nonlinearities, the plasma waves could detect both the radiation intensity and the phase enabling the line-of-sight terahertz (THz) detection, spectrometry, amplification, and generation for 6G communication.
We report on the response characteristics of plasmonic terahertz field-effect transistors (TeraFETs) fed with femtosecond and picosecond pulses. Varying the pulsewidth (<inline-formula> <tex-math ...notation="LaTeX">{t}_{\textit {pw}} </tex-math></inline-formula>) from 10 −15 s to 10 −10 s under a constant input power condition revealed two distinctive pulse detection modes. In the short pulse mode (<inline-formula> <tex-math notation="LaTeX">{t}_{\textit {pw}} \ll {L}/{s} </tex-math></inline-formula>, where <inline-formula> <tex-math notation="LaTeX">{L} </tex-math></inline-formula> is the gated channel length and <inline-formula> <tex-math notation="LaTeX">{s} </tex-math></inline-formula> is the plasma velocity), the source-to-drain voltage response is a sharp pulse oscillatory decay preceded by a delay time on the order of <inline-formula> <tex-math notation="LaTeX">{L}/{s} </tex-math></inline-formula>. The plasma wave travels along the channel like the shallow water wave with a relatively narrow wave package. In the long pulse mode (<inline-formula> <tex-math notation="LaTeX">{t}_{\textit {pw}} > {L}/{s} </tex-math></inline-formula>), the response profile has two oscillatory decay processes and the propagation of plasma wave is analogous to an oscillating rod with one side fixed. The ultimate response time at the long pulse mode is significantly higher than that under the short pulse conditions. The detection conditions under the long pulse mode are close to the step response condition, and the response time conforms well to the analytical theory for the step function response. The simulated waveform agrees well with the measured pulse response. Our results show that the measurements of the pulse response enable the material parameter extraction from the pulse response data (including the effective mass, kinematic viscosity, and momentum relaxation time).
We show that vapors of different chemicals produce distinguishably different effects on the low-frequency noise spectra of graphene. It was found in a systematic study that some gases change the ...electrical resistance of graphene devices without changing their low-frequency noise spectra while other gases modify the noise spectra by inducing Lorentzian components with distinctive features. The characteristic frequency f c of the Lorentzian noise bulges in graphene devices is different for different chemicals and varies from f c = 10–20 Hz to f c = 1300–1600 Hz for tetrahydrofuran and chloroform vapors, respectively. The obtained results indicate that the low-frequency noise in combination with other sensing parameters can allow one to achieve the selective gas sensing with a single pristine graphene transistor. Our method of gas sensing with graphene does not require graphene surface functionalization or fabrication of an array of the devices with each tuned to a certain chemical.
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