Power measurement setup for large signal microwave characterization at 94 GHz

We report the development of a power measurement setup in order to characterize devices at 94GHz. A very careful calibration of the setup has been performed in order to take into account in a most accurate way the losses through the different parts of the bench and in particular through the tuner. These aware power measurements have allowed to demonstrate state of the art power results on two different devices. We reached at 94GHz an output power of 876mW/mm associated to a 7.5-dB power gain and a power added efficiency (PAE) of 33% on a pseudomorphic high electron mobility transistor (PHEMT) on GaAs substrate. We achieved a 260-mW/mm maximum output power density with 5.9-dB power gain and 11% PAE on an InAsP channel HEMT on InP substrate.     

High-efficiency uni-travelling-carrier photomixer at 1.55 μm and spectroscopy application up to 1.4 THz

The fabrication of InGaAs/InP uni-travelling-carrier photodiodes integrated with broadband horn antennas and demonstration of photomixing up to 1.8THz are reported. A radiated power of 1.1 μW at 940 GHz was measured for a photocurrent of only 2.75 mA (50 mW optical power), demonstrating the high efficiency of the device. The conversion efficiency obtained has been increased by more than a decade compared to the best reported values in the literature. The photomixer is used to identify the 1411 GHz water vapour absorption line at atmospheric pressure.     

Metamorphic In0.4Al0.6As/In0.4Ga0.6As HEMTs on GaAs substrate

New In_0.4Al_0.6As/In_0.4Ga_0.6 As metamorphic (MM) high electron mobility transistors (HEMTs) have been successfully fabricated on GaAs substrate with T-shaped gate lengths varying from 0.1 to 0.25 μm. The Schottky characteristics are a forward turn-on voltage of 0.7 V and a gate breakdown voltage of -10.5 V. These new MM-HEMTs exhibit typical drain currents of 600 mA/mm and extrinsic transconductance superior to 720 mS/mm. An extrinsic current cutoff frequency f_T of 195 GHz is achieved with the 0.1-μm gate length device. These results are the first reported for In_0.4 Al_0.6As/In_0.4Ga_0.6As MM-HEMTs on GaAs substrate     

60-GHz high power performance In/sub 0.35/Al/sub 0.65/As-In/sub 0-35/Ga/sub 0.65/As metamorphic HEMTs on GaAs

We report on a double-pulse doped, double recess In/sub 0.35/Al/sub 0.65/As-In/sub 0.35/Ga/sub 0.65/As metamorphic high electron mobility transistor (MHEMT) on GaAs substrate. This 0.15-/spl mu/m gate MHEMT exhibits excellent de characteristics, high current density of 750 mA/mm, extrinsic transconductance of 700 mS/mm. The on and off state breakdown are respectively of 5 and 13 V and defined It gate current density of 1 mA/mm. Power measurements at 60 GHz were performed on these devices. Biased between 2 and 5 V, they demonstrated a maximum output power of 390 mW/mm at 3.1 V of drain voltage with 2.8 dB power gain and a power added efficiency (PAE) of 18%. The output power at 1 dB gain compression is still of 300 mW/mm. Moreover, the linear power gain is of 5.2 dB. This is to our knowledge the best output power density of any MHEMT reported at this frequency.     

Hemt’s capability for millimeter wave applications

This paper presents a tutorial review on the High Electron Mobility Transistors (HEMTs)for low-noise and power applications at millimeter wave range frequencies. The major parameters to achieve high performance with such devices are discussed. Present status on power and noise performances is given for InAlAs/InGaAs HEMTs on InP and GaAs substrates.     

InP HEMT downscaling for power applications at W band

We have developed new solutions for InP high-electron mobility transistor (HEMT) scaling for power applications at W band. We have shown that the use of a small barrier thickness in order to respect the aspect ratio for a 70-nm gate length results in a significant kink effect and high gate source capacitances. We have also shown through a theoretical study that a structure containing an InP layer between the cap layer and the barrier would support both the frequency performances and the breakdown voltage. Thus, we propose an HEMT structure containing a thick InP/AlInAs composite barrier and where the gate is buried into the barrier. This enables us to respect the aspect ratio and simultaneously to obtain an important drain current density without observing any kink effect. Moreover, we have applied this process to structures containing innovative large band-gap InP and InAsP channels. We have achieved the best frequency performances ever reached for an InP channel HEMT structure. Power measurements at 94 GHz were performed on these devices. The InAsP channel HEMT demonstrated a maximum output power of 260 mW/mm at 3 V of drain voltage with 5.9-dB power gain and a power-added efficiency of 11%. These results are favorably comparable to the state-of-the-art of InP-based HEMT at this frequency.     

InAlAs/InGaAs metamorphic HEMT with high current density and highbreakdown voltage

An In_0.3Al_0.7As/In_0.3Ga_0.7 As metamorphic power high electron mobility transistor (HEMT) grown on GaAs has been developed. This structure with 30% indium content presents several advantages over P-HEMT on GaAs and LM-HEMT on InP. A 0.15-μm gate length device with a single δ doping exhibits a state-of-the-art current gain cut-off frequency F_t value of 125 GHz at V_ds=1.5 V, an extrinsic transconductance of 650 mS/mm and a current density of 750 mA/mm associated to a high breakdown voltage of -13 V, power measurements performed at 60 GHz demonstrate a maximum output power of 240 mW/mm with 6.4-dB power gain and a power added efficiency (PAE) of 25%. These are the first power results ever reported for any metamorphic HEMT