Study On GaN-based Millimeter-wave Device With Heterostructure

GaN-based millimeter-wave device technology has become the most promising technology in millimeter-wave high-power devices and power amplifier. Because of its excellent microwave power characteristics the GaN device has broad application prospects in the military, commercial and consumer areas. To reduce HEMT's gate length is the most effective way to improve devices'power and gain at high frequency. So how to overcome short-channel effect is a key factor in development of millimeter-wave devices.This paper firstly researched the structure of thin barrier layer of AlGaN/GaN heterostructure. According to our research an appropriate increase of the AlN barrier insertion layer thickness is very helpful to inhibit the reduction of 2DEG. In this way, we achieved a thin barrier layer structure with a high 2DEG density without raising Al composition of the barrier layer. With the advantage of this thin barrier layer structure, a high frequency device was fabricated. The fT of it is 31GHz and fMAX is 70GHz. The maximum transconductance of the device is up to 340mS/mm and the threshold voltage of it is only -1V. With good turn-off characteristics, the device overcomes the short-channel effects well. After analysis, we believe that self-heating effect is one of the most important factors which cause device performance degradationRecessed-gate structure can increase gate control capability under the premise of thick barrier layer. This paper lucubrated the mechanism of the material injury brought by etching and analyzed the device properties'change over etching time. We finalize the best etching time through comparative experiments. A high-frequency, high-quality recessed gate device was fabricated which exhibiting a high Idmax of 1200mA/mm and the maximum transconductance of the device is up to 350mS/mm. The fT of it is 60GHz, and fMAX is up to 105GHz.