A STUDY OF SIDE GATE TEST STRUCTURES IN INALAS INGAAS HEMTS FOR OPTOELECTRONIC CIRCUIT APPLICATIONS/

The InAlAs/InGaAs HEMT is a key electron device used in optoelectronic integrated circuits (OEICs) operating in the 1.3 and 1.5 mu m optical wavelength ranges. OEIC performances can be degraded by side-gating e ffects associated with the HEMT. A side gate current is evidenced and demonstrated to be (i) due to a hole current induced by an impact ioni zation mechanism into the HEMT InGaAs channel and flowing through the InAlAs buffer layer and (ii) strongly dependent on the side gate test structure geometries and types of contacts. Finally, an optimized stru cture for monolithic integration is presented to ether with requiremen ts on the operating point.