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MOSFETs for RF Applications
Published in Frank Schwierz, Hei Wong, Juin J Liou, Nanometer CMOS, 2010
Frank Schwierz, Hei Wong, Juin J Liou
For a long time, the εbar/tbar ratio has not been considered as being very critical for HEMT performance, while scaling the oxide thickness has been an integral part of the MOSFET scaling philosophy since decades. This can be seen from Fig. 4.25 showing the scaling trend of the barrier thickness for MOSFETs and HEMTs. The less consequent scaling of the barrier thickness is one reason for the fact that it took 12 years to double fT of III-V HEMTs (250 GHz in 1990 vs 500 GHz in 2002), but only 6 years to double fT of Si MOSFETs (245 GHz 2001 vs 485 GHz in 2007). It is important to recognize, however, that it is much more difficult to thin down the barrier in HEMTs than in MOSFETs. HEMT barriers are semiconductors while the MOSFET barrier is an insulator showing a much larger bandgap and also much larger band offsets at the barrier-channel interface.
Nanotubes and Their Applications in Telecommunications
Published in Anwar Sohail, Raja M Yasin Anwar Akhtar, Raja Qazi Salahuddin, Ilyas Mohammad, Nanotechnology for Telecommunications, 2017
Although today’s state-of-the-art transistors are characterized by a physical gate length of approximately 50 nm, research groups in industry and academia have already demonstrated devices with gate lengths close to 30 nm. A 15 nm HEMT with a maximum frequency speed of 610 GHz was reported in 2008.
The Analysis Model of AlGaN/GaN HEMTs with Electric Field Modulation Effect
Published in IETE Technical Review, 2020
Luoyun Yang, Baoxing Duan, Ziming Dong, Yandong Wang, Yintang Yang
Gallium nitride (GaN) is one of the third generation of wide-bandgap semiconductor materials without the inherent shortcomings of the first two generations of semiconductor materials, like Si and GaAs. Due to its wide band gap (> = 3.4 eV), high breakdown field (3MV/cm), high electron saturation speed (>2 × 107cm/s), high thermal conductivity and excellent properties, GaN material is suitable for high-power, high-temperature, and high-frequency applications [1]. GaN power devices [2] are considered to be the core of next-generation power devices, especially for the AlGaN/GaN heterojunction material system. High concentration (>1 × 1013cm−2) and mobility (1000–2000 cm2/V. s) 2DEG are generated at the interface of the heterojunction because the spontaneous polarization and piezoelectric polarization effects [3–5]. High electron mobility transistor (HEMT) has developed rapidly in recent years based on this heterojunction material system [6–9]. In high-power AlGaN/GaN HEMT devices, the breakdown voltage (BV) is a key parameter that we need to consider [10]. Researchers have designed many methods and techniques to get higher breakdown voltage and lower specific on-resistance, such as increase of breakdown voltage on AlGaN/GaN HEMTs by employing proton implantation [11], AlGaN/GaN HEMTs with integrated slant field plates [12], the new RESURF AlGaN/GaN HEMTs [13] and so on [14–16].
2-D optimisation current–voltage characteristics in AlGaN/GaN HEMTs with influence of passivation layer
Published in International Journal of Ambient Energy, 2021
Abdelmalek Douara, Abdelaziz Rabehi, Bouaza Djellouli, Abderrezzaq Ziane, Hamza Abid
The basic concept in a HEMT is the aligning of a wide and narrow bandgap semiconductor adjacent to each other in order to form a hetero-junction (Chan et al. 1990). In a typically doped AlGaN/GaN HEMT structure, the AlGaN donor (carrier supply) layer supplies electrons to the 2DEG (Meng et al. 2012). The 2DEG is formed at the AlGaN/GaN interface even if all the layers are grown without intentional doping. In fact, the contribution of the doping to the 2DEG sheet carries concentration is reported to be less than 30% due to the stronger piezoelectric effect in the material system (Kumar and Bindu 2012).