Performance enhancement of Deep Recess N-polar MISHEMTs for 94 GHz operation via electric field shaping in the GaN channel
Abstract
Performance enhancement of Deep Recess N-polar MISHEMTs for 94 GHz operation via electric field shaping in the GaN channelStatement of WorkFunds are provided to develop n-polar GaN HEMTs for RF applicationsThe PI is Prof. Umesh Mishra at the University of California, Santa Barbara.This is a 36-month grantThis grant will investigate approaches to enhancing electron transport in nitrogen polar HEMTs at 94 GHz. The device structures of N-Polar Deep-Recess (NPDR) MISHEMTs will be optimized by lowering the electric field in the GaN channel via insertion of a thin InGaN layer. This inserted InGaN layer will lead to an increase in both the sheet charge and mobility of the two dimensional electron gas (2DEG), facilitating further vertical and lateral scaling of the transistors. Moreover, the insertion of an InGaN layer will result in a stronger reverse electric field in the AlGaN cap layer under the gate enabling higher break down voltages. Furthermore, in the access regions, the insertion of an InGaN layer between the GaN channel and AlGaN cap will remove the secondary 2DEG seen at the AlGaN cap/GaN cap interface in previous NPDR MISHEMTs. All benefits will result in an improved device performance at 94 GHz.ObjectiveInvestigate approaches to enhancing electron transport in nitrogen polar HEMTs at 94 GHz in order to improve device performance and breakdwon voltage.Approach(a) Optimization of the epitaxial growth process: Optimization of the InzGa1-xN deposition process to reduce lateral variations in the alloy composition, with the intent of preventing alloy scattering of the channel 2DEG. Optimization of the AlGaN etch stop and GaN Cap epitaxial growth process at lower temperatures. This is to prevent thermal decomposition of the underlying InxGa1-xN layer, whose thermal stability is lower than that of typical (Al,Ga)N films.(b) Optimization of the thickness and composition of the graded InGaN layer and the GaN channelfor optimum device performance:Samples with different graded InGaN layer thicknesses, InxGa1-xN compositions, and GaN channel layer thicknesses will be grown, processed and tested. The DC and RF performance of the devices will be evaluated by DC-IV, small signal RF, and breakdown voltage measurements. Potential dispersion in the devices will be examined by conducting pulsed IV measurements with a pulse width down to 200 ns. The output power of the devices will be determined by load-pull measurement at 94 GHz.RelevanceThis effort builds on two prior D&I projects, nitrogen-polar W-band devices and the MINE MURI (mm-wave GaN HEMTs). This effort will investigate the impact of enhanced electron transport in the source and channel. If this is successful, then a significant improvement in device properties is expected. This will to significant performance advances for naval mm-wave sensors and communication systems.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Sep 30, 2016
- Source ID
- N000141612931
Entities
People
- Umesh Mishra
Organizations
- Office of Naval Research
- United States Navy
- University of California, Santa Barbara