Terahertz Schottky Diode Device with High Cutoff Frequency Developed in IMECAS

http://english.cas.cn/ST/HT/ht_progress/201211/t20121105_94876.shtml
Terahertz Schottky diode with the cutoff frequency of 3.37THz and quartz circuit applied in terahertz band were developed in the Institute of Microelectronics of Chinese Academy of Sciences (IMECAS). After verification by experiment in the 41th Institute of China Light & Power (CLP) Group, performance of this device was similar to those of overseas product.
Terahertz (THz, 1THz = 10~(12)Hz) wave with a frequency range of 0.1-10.0 THz, sandwiched between microwave and infrared, belongs to far infrared region. It was elected as one of the “Ten Major” technologies that can change the world in the future by USA because of its unique physical and chemical properties.
The THz device and circuit research group in Microwave Devices and Integrated Circuits Department of IMECAS researched on the key techniques of THz circuit. They designed and optimized the growth of epitaxial layer and realized breakthroughs in key technologies such as ohmic contact alloys with low-resistivity, schottky micro etching, air-bridge etch technologies and so on, which decreased the series resistance and stray capacitance effectively. The schottky diode research group developed can be applied in THz wave range. What’s more, they developed several integration technologies for schottky diodes (Fig.1). Cutoff frequency of the THz schottky diode device (Fig.2) has already led to 3.37THz, which can be widely used in the detection, double-frequency and frequency mixing of THz waves.
In order to solve the high loss of peripheral circuits, the research group developed thickness reduction technology for backside of substrate and realized THz circuit by using low dielectric quartz material. The core circuit with the thickness smaller than 50µm applied in THz band (Fig.3) decreases the loss in THz band efficiently, which enhance the efficiency of circuitry.
This THz schottky diode also realized double-frequency in THz wave, with the frequency doubling efficiency of 3.6% in 170~220 GHz, 1.0% in 220~325 GHz (Fig.4). The frequency multiplier can be used in the building of broadband THz source, with a wide application in THz wave imaging, THz communication and Satellite RS (remote sensing) technology.

(a)	(b)	(c)

Fig.1 Multiple Cascade Structures of Different THz Schottky Diodes (a) Single Diode (b) Series Diodes (c) Pair Diodes (Image by IMECAS)

Fig.2 Cutoff Frequencies of THz Schottky Diodes with Different Junction Areas (Image by IMECAS)

Fig.3 Photograph of Quartz Core Circuit (Image by IMECAS)

Fig.4 Output of the Example Test for Frequency Multiplier with THz Schottky Diode (Contrasting with VDI Diode ) (Image by IMECAS)

CONTACT:
JIN Zhi
Institute of Microelectronics of Chinese Academy of Sciences
E-mail: jinzhi@ime.ac.cn
Website of Dept.: http://english.ime.cas.cn/Research/ResearchDivisions/LAB4