Parabolic Grading of a PHEMT Channel Composition for Ultra-High and Broad OIP3 Peak

A. Ramu1, K. -Y. Ban2, D. Kimpton1, S. Wilson1, and R. Bayruns3
1Silvaco Inc., Santa Clara, CA, USA. email:
2LG Display, Yeongdeungpo-gu, Seoul, South Korea 3GGB Industries, Naples, Florida, USA; XG Micro, Raritan, NJ, USA

We detect a local maximum in the design space of a pseudomorphic-channel high electron mobility transistor (PHEMT). The design has an OIP3  linearity figure-of-merit that is 10-15 dBm above the baseline for a similar 1 mm width control device, and is achieved at a gate bias on the order of 100 mA/mm or less, where the ratio of transconductance to the bias current gm1/ID is particularly large (7 volt-1).

However, this local maximum is very narrow with respect to barrier thickness and delta-doping. We find that parabolic grading of the channel composition increases the height and width of the peak, rendering the design stable to the presence of inevitable process variations. Simulations of the device in quasi-static and time-dependent modes using Atlas™ of the Silvaco® suite of technology computer-aided design (TCAD) tools demonstrate the validity of the design.