Off-state breakdown in InAlAs/InGaAs MODFET's

• Published in: IEEE transactions on electron devices 1995-01, Vol.42 (1), p.15-22
• Main Authors: Bahl, S.R., del Alamo, J.A., Dickmann, J., Schildberg, S.
• Format: Article
• Language: English
• Subjects: Applied sciences; Dielectrics and electrical insulation; Electric breakdown; Electron emission; Electronics; Exact sciences and technology; HEMTs; Indium compounds; Indium gallium arsenide; Indium phosphide; MODFETs; Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Temperature; Transistors
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/16.370041

Recent efforts are being focussed on improving the breakdown voltage (BV) of InAlAs/InGaAs MODFET's on InP towards high-power applications. A detailed understanding of the physics of breakdown in these devices is still lacking. In this paper, we carry out a study of off-state breakdown on state-of-the-art MODFET's in this material system. Through a combination of a surface-depleted cap and mesa-sidewall isolation the devices have BV's of around 10 V. We find that BV shows a negative temperature coefficient and also decreases with a higher InAs mole fraction in the channel. As we have recently found in InAlAs/n/sup +/-InGaAs HFET's, off-state breakdown appears to be a two-step process. First, electrons are emitted by thermionic-field emission from the gate to the insulator. Second, as a consequence of the large electric field in the insulator and the substantial /spl Delta/E/sub C/ between insulator and channel, they enter the channel hot, into the high-field drain-gate region, and relax their energy through impact-ionization. This combined hypothesis is able to explain why the MODFET breakdown voltage depends on both channel and insulator design parameters.< >