Breakdown characterization of AlInAs/GaInAs junction modulated HEMTs (JHEMTs) with regrown ohmic contacts by MOCVD

We present a technology to increase both the two-terminal gate-drain breakdown and subsequently the three-terminal-off-state breakdown of AlInAs/GaInAs HEMTs to record values without substantial impact on other parameters such as Idss and g/sub m/. The breakdown in these structures is dependent on the injection of electrons from the source (channel current) and the gate (gate leakage) into the channel where multiplication occurs (due to high electric fields at the drain), producing holes which are swept back into the gate and source electrodes. These phenomena can be suppressed by increasing the gate barrier height and alleviating the fields at the drain. In our approach we have achieved both by incorporating a p+-2DEG junction as the gate which modulates the 2DEG gas and by utilizing selective regrowth of the source and drain regions by MOCVD. The 1 /spl mu/m gate length devices fabricated show a full channel current of 350 mA/mm, transconductance of 240 mS/mm and record high two-terminal gate-drain and three-terminal-off-state breakdown voltages of 31 V and 28 V, respectively. The gate-to-drain spacing is 1/spl mu/m and the breakdown is defined at 1mA/mm gate leakage. Further, temperature measurements were made to characterize both two-terminal and three-terminal-on-state breakdown. The gate current behavior is presented along with a calculated ionization rate which is compared with rates previously reported.<
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