**7. Future trends**

with low bias power. The result is verified designing Colpitt and negative resistance oscilla‐

**Figure 9.** Output power performance of GaN HEMT power amplifier MMIC with frequency variation in pulse and CW

Crupi et al. investigated Kink effect (KE) in advanced GaN HEMT technology [26]. For better understanding, KE is studied comprehensively with change of temperature and bias conditions. It is shown that the dependence of KE on operating conditions is mainly due to device transcon‐ ductance. Characterization of anomalous KE would be a useful tool for microwave engineers who need this knowledge of KE for designing and modeling devices with GaN HEMTs.

A total of 600 V GaN HEMT switches have been demonstrated experimentally to show per‐ formance comparison with silicon‐based transistor switches such as IGBTs and MOSFETs [27]. HEMT switches, despite being beginners, show excellent performance compared to the matured counterparts, Si‐based MOSFETs. It is shown that GaN switches offer higher boost converter efficiency than the MOSFET switches. Next, GaN switches are compared experimentally with IGBTs. Both Si body and SiC body‐based IGBTs have been considered. It is found that at higher switching frequency, IGBT switches loss efficiency very rapidly, while HEMT switches loss effi‐ ciency monotonically as shown in **Figure 10**. Therefore, HEMTs offer superior performance to Si‐based MOSFETs and IGBTs for high frequency power converter switching applications.

tors and both of these present so far the best reported FOMs.

**6.6. 600 V GaN HEMT switches for power converters**

**6.5. Kink effect in GaN HEMT technology**

56 Different Types of Field-Effect Transistors - Theory and Applications

modes.

The future HEMT devices based on two‐dimensional carrier confinement seem very bright in electronics, communications, physics, and other disciplines. GaAs, InP, and GaN‐based HEMTs will continue their journey toward higher integration, higher frequency, higher power, higher efficiency, lower noise, and lower cost. GaN, in particular, offers high‐power, high‐frequency territory of vacuum tubes and leads to lighter, more efficient, and more reli‐ able communication systems.

HEMTs will continue to mold themselves into other kinds of FETs that will exploit the unique properties of 2DEG in various materials systems. In power electronics, GaN‐based HEMTs can create a great impact on consumer, industrial, transportation, communication, and mili‐ tary systems. On the other hand, MOS‐HEMT or MISFET structures are likely to be operated in enhancement mode with very low leakage current.

Si CMOS technology is rapidly advancing toward 10 nm gate regime. To achieve this, power dissipation management in future generation ultra‐dense chips will be a significant chal‐ lenge. Operating voltage reduction may be a solution to meet this challenge. However, cur‐ rently, it is difficult to accomplish this with Si CMOS while maintaining quality performance. Quantum well‐based devices such as InGaAs or InAs HEMTs offer very high potential. Therefore, HEMTs may extend the Moore's law for several more years which will be gigantic for the society [28].

From the past, it can be anticipated that, researching on new device models and structures of HEMTs will definitely result in new insights into the often bizarre physics of quantized electrons. ZnO, SiGe, and GaN have shown fractional quantum Hall effect (FQHE), the greatest exponent for impeccable purity and atomic order, which ensure the bright future of HEMT devices [29].

The concept of different kinds of physical and biosensors are still very new to these kind of devices. The ultra‐high mobility that is possible in InAlSb/InAsSb‐based system enables high‐ sensitivity micro‐Hall sensors for many applications including scanning Hall probe microscopy and biorecognition [30]. Three‐axis Hall magnetic sensors have been reported in micromachined AlGaAs/GaAs‐based HEMTs [31]. These devices may be used in future electronic compasses and navigation. THz detection, mixing and frequency multiplication can also be used by 2DEG‐based devices [32]. GaN and related materials have strong piezoelectric polarization, and they are also chemically stable semiconductors. Combining functionalized GaN‐based 2DEG structures with free‐standing resonators, there is a possibility of designing sophisticated sensors [33]. These can offer methods of measurements of several properties such as viscosity, pH, and temperature.

Without references, expansion of this technology in the machine to machine (M2M) field is expected to be used in cloud networking‐based various sensing functions. Diverse applica‐ tions such as environmental research, biotechnology, and structural analysis can be greatly benefited with the help of newly emerged sensing technology which has high speed, high mobility, and high sensitivity characteristics. HEMT technology is expected to make a great change in the intelligent social infrastructure from the device level. A smart city system, transport system, food industry, logistics, agriculture, health welfare, environmental sci‐ ence, and education systems are examples where this technology can make exceptions [34].

The rise of III‐N‐based solid‐state lighting will lead to a continuous development of materials, substrates, and technologies pushed by a strong consumer market. In an analogy, III‐N optoelec‐ tronics will challenge the light bulbs, while III‐N electronics will challenge the electronic equiva‐ lent, the tubes [35].
