IN(0.52)A(0.48)AS INXGA1-XAS (0.53-LESS-THAN-X-LESS-THAN-1.0) PSEUDOMORPHIC HIGH-ELECTRON-MOBILITY TRANSISTORS WITH HIGH BREAKDOWN VOLTAGES- DESIGN AND PERFORMANCES/

The search for suitable ways to improve the high electron mobility tra nsistors (HEMT's) device performances has stimulated the turbulent res earch work on pseudomorphic layer structures. Recent interest has been focused on pseudomorphic InAlAs/InGaAs HEMTs. In this paper we report on the design and fabrication of In0.52Al0.48As/InxGa1-xAs (0.53 < x < 1.0)-pseudomorphic HEMTs. The main subject of the simulation and exp erimental work is the design of the channel to allow a maximum InAs mo lefraction ion while maintaining excellent device performance. The gen eral results of our investigation are that the current handling capabi lity and the high speed performance improves with x, while the breakdo wn voltage Continuously degrades with increasing x. From our investiga tion an indium molefraction of x = 0.7 was found to be optimum for the high speed performance.