Voltage controlled sub-THz detection with gated planar asymmetric nanochannels

[EN]This letter reports on room temperature sub-THz detection using self-switching diodes based on an AlGaN/GaN heterostructure on a Si substrate. By means of free-space measurements at 300 GHz, we demonstrate that the responsivity and noise equivalent power (NEP) of sub-THz detectors based on planar asymmetric nanochannels can be improved and voltage controlled by means of a top gate electrode. A simple quasi-static model based on the DC measurements of the current-voltage curves is able to predict the role of the gate bias in its performance. The best values of voltage responsivity and NEP are achieved when the gate bias approaches the threshold voltage, around 600 V/W and 50 pW/Hz1/2, respectively. A good agreement is found between modeled results and those obtained from RF measurements under probes at low frequency (900MHz) and in free-space at 300 GHz

Influence of recess and epilayers in the 26 – 40 GHz band HEMT’s intermodulation

The comparison of the linearity performance for three PHEMTs have been investigated in Ka band. The studied transistors are a single recessed PHEMT, a double recessed PHEMT and a double recessed dual channel PHEMT. The main result is : at a given output power level, the double recess allows a large improvement of the intermodulation ratio (IMR), thanks to its higher drain-source bias voltage capability, compared to the single recess. The second result is : the double recessed PHEMTs comparison shows that the dual channel, thanks to a more wide and uniform ransconductance distribution than the single channel, is a better solution for linearity application at 26GHz

Hemt structures and technology on GAAS and inp for power amplification in millimetre wave range

The paper introduces a simple and efficient approach for the modelling of low-frequency dispersive phenomena in FETs. It is based on the definition of a virtual, non-dispersive associated device controlled by equivalent port voltages and it is suitable for modelling based on standard nonlinear dynamic approaches, such as lumped-element equivalent circuits. The proposed approach is justified on the basis of a physically-consistent, charge-controlled description of the device, but the results are general and provide a valuable tool for taking into account dispersive effects in FETs by means of an intuitive circuit solution, in the framework of any existing nonlinear dynamic model of the associated non-dispersive device. The new equivalent-voltage description, identified on the basis of conventional measurements carried out under static and small-signal dynamic operating conditions, allows for the accurate prediction of dispersive effects above the frequency cut-off, but the formulation is still compatible, without for al modification, for the modelling of the device behaviour under signal excitations having spectral components in the dispersive low-frequency range. Preliminary results are presented which conferm the validity of the proposed approach

On-Wafer Series-Through Broadband Measurement of Sub-fF55-nm MOS RF Voltage-Tunable Capacitors

International audienceThe objective of this letter oriented towards microwave measurement of high impedance devices using a conventional on-wafer probe station is multiple. First, we provided a quantification of the measurement uncertainty inherent to the setup when measuring capacitors in the range 0.01-10 fF using both reflection and transmission methods up to 50 GHz. In particular, we demonstrate a clear improvement when using transmission method in series-through configuration. As a practical demonstration, on-wafer MOS voltage-tunable capacitors with capacitances ranging from 0.85 to 1.15 fF are extracted with uncertainties of 130 and 2 aF respectively for both reflection and transmission measurements at 10 GHz. Capacitance fluctuation related to the technological process in the order of 20 aF is then exemplary demonstrated using the series-through configuration. Index Terms-sub-fF MOS varactor, measurement accuracy, on-wafer calibration, vector network analyzer (VNA), two-port measurement, coplanar waveguide (CPW)

Parasitic effects and traps in AlGaN/GaN HEMT on sapphire substrate

AlGaN/GaN high electron mobility transistors (HEMTs) with sapphire (Al2O3) substrates reveal anomalies like kink effect, current collapse, hysteresis phenomena on Ids-Vds and Ids-Vgs. These parasitic effects can be attributed to the presence of traps in the hetero-structure. Deep defects analysis was performed by conductance deep level transient spectroscopy (CDLTS) under drain pulse. Four electron traps have been detected with activation energy and capture cross-section of 2.62 eV, 1.18 eV, 0.97 eV, 0.48 eV, σn = 2.4 × 10-17 cm2 and σn = 2.37 × 10-14 cm2, σn = 2 × 10-12 cm2 and σn = 4.67 × 10-14 cm2 respectively. The localisation and the identification of these traps have occurred and a correlation between defects and parasitic effects has been discussed

Modelling and Design of a Wideband 6-18 GHz GaN Resistive Mixer

A wideband hybrid AlGaN/GaN Resistive Mixer has been designed and simulated. The cold-FET mixer is based on a 2*100*0.25 μm² AlGaN/GaN HEMT in a single-ended circuit topology. An application-specific empirical transistor model has been extracted and validated in small- and large-signal conditions, in order to carry out the mixer design and simulations. This mixer presents an IF bandwidth of 6 GHz with a conversion loss < 16 dB for each RF and LO frequency choice from 6 up to 18 GHz

Recent Developments and Trends in GaN HFETs

This paper reviews the main challenges and results concerning GaN HFET research and development in Europe. Today several actors are working to allow the emergence of an European source for this technology. The activity sweeps all R&D fields from material growth to circuit realization and reliability

‘Characterization of the self-heating of AlGaN/GaN HEMTs during an electrical stress by using the Raman spectroscopy’

International audienc

‘Neutron irradiation effects on the electrical properties of previously electrically stressed AlInN/GaN HEMTs’

International audienc