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Bulk Acoustic Wave (BAW) filters find applications in radio frequency (RF) communication systems for Wi-Fi, 3G, 4G, and 5G networks. In the beyond-5G (potential 6G) era, high-frequency bands (>8 GHz) are expected to require resonators with high-quality factor ( Q ) and electromechanical coupling ( k t 2 ) to form filters with low insertion loss and high selectivity. However, both the Q and k t 2 of resonator devices formed in traditional uniform polarization piezoelectric films of aluminum nitride (AlN) and aluminum scandium nitride (AlScN) decrease when scaled beyond 8 GHz. In this work, we utilized 4-layer AlScN periodically poled piezoelectric films (P3F) to construct high-frequency (~17–18 GHz) resonators and filters. The resonator performance is studied over a range of device geometries, with the best resonator achieving a k t 2 of 11.8% and a Q p of 236.6 at the parallel resonance frequency ( f p ) of 17.9 GHz. These resulting figures-of-merit are ( FoM 1 = k t 2 Q p and FoM 2 = f p FoM 1 × 10 − 9 ) 27.9 and 500, respectively. These and the k t 2 are significantly higher than previously reported AlN/AlScN-based resonators operating at similar frequencies. Fabricated 3-element and 6-element filters formed from these resonators demonstrated low insertion losses (IL) of 1.86 and 3.25 dB, and −3 dB bandwidths (BW) of 680 MHz (fractional BW of 3.9%) and 590 MHz (fractional BW of 3.3%) at a ~17.4 GHz center frequency. The 3-element and 6-element filters achieved excellent linearity with in-band input third-order intercept point (IIP3) values of +36 and +40 dBm, respectively, which are significantly higher than previously reported acoustic filters operating at similar frequencies.

Nitride-based semiconductors are gaining importance not only for high-power applications but also for high-temperature electronic devices. Using photoluminescence (PL) techniques, it is now possible to simultaneously determine the temperatures of the lattice and hot electrons in these devices. Therefore, it is possible to use PL mapping measurements to derive temperature profiles for electrons and the lattice in the active region of an operating device with a single set of measurements. This work presents an experimental process to construct such spatially resolved temperature maps for a planar semiconductor device under bias and applies this approach to a specific example using the conductive channels of a biased AlGaN/GaN high-electron-mobility transistor. Studying the temperature distribution inside the conductive channels will help understand how electrons flowing in the device interact with the lattice as well as the process of heat generation within the device.

Under class AB bias and CW opera- tion at 3.3 GHz, a typical 2.2 mm unit cell device obtains 56 percent peak power added effi- ciency (PAE) and a peak output power of 21.9 W. This cor- responds to a power density of 9.9 W/mm. This is about three times the 3.2 W/mm power density obtained at 28 V drain bias from a device without the field plate. The series equivalent optimum source and load impedances are Zsub s= 3.8 +j10.5 ohm and Zsub l=30 +j47 ohm, respectively.

An optical receiver for 40 Gbit/s communication systems with 8,274 V/W conversion gain and 950 mVp-p limiting differential output is reported. A back-to-back sensitivity of -9.4 dBm at a bit error rate of 10...12 was observed for a 231-1 pseudorandom binary sequence. The receiver incorporates an InP based pin diode, a transimpedance amplifier and a limiting amplifier. This is the largest conversion gain with high sensitivity reported for 40 Gbit/s receivers without optical amplification.

An optical receiver for 40 Gbit/s communication networks demonstrating very high sensitivity without optical amplification has been developed. The receiver comprises an InP-based pin diode and HBT transimpedance amplifier. The receiver achieves a back-to-back sensitivity of -9 dBm and a high dynamic range of 13 dBm, measured using a pseudorandom binary sequence of 2^sup 31^ -1 at a bit error rate of 10^sup -12^. These results, show the highest sensitivity and widest dynamic range yet reported for 40 Gbit/s optical receivers without optical amplification.

Bulk Acoustic Wave (BAW) filters find applications in radio frequency (RF) communication systems for Wi-Fi, 3G, 4G, and 5G networks. In the beyond-5G (potential 6G) era, high frequency bands (>8 GHz) are expected to require resonators with high-quality factor (Q) and electromechanical coupling (k_t^2) to form filters with low insertion loss and high selectivity. However, both the Q and k_t^2 of resonator devices formed in traditional uniform polarization piezoelectric films of aluminum nitride (AlN) and aluminum scandium nitride (AlScN) decrease when scaled beyond 8 GHz. In this work, we utilized 4-layer AlScN periodically poled piezoelectric films (P3F) to construct high frequency (~17-18 GHz) resonators and filters. The resonator performance is studied over a range of device geometries, with the best resonator achieving a k_t^2 of 11.8% and a Q_p of 236.6 at the parallel resonance frequency (fp) of 17.9 GHz. These resulting figures of merit are ((FoM)_1=(k_t^2 Q)_p and (FoM_2=f_p(FoM)_1x10^-9) ) 27.9 and 500 respectively. These and the k_t^2 are significantly higher than previously reported An/AlScN-based resonators operating at similar frequencies. Fabricated 3-element and 6-element filters formed from these resonators demonstrated low insertion losses (IL) of 1.86 dB and 3.25 dB, and -3 dB bandwidths (BW) of 680 MHz (fractional BW of 3.9%) and 590 MHz (fractional BW of 3.3%) at ~17.4 GHz center frequency. The 3-element and 6-element filters achieved excellent linearity with in-band input third-order intercept point (IIP3) values of +36 dBm and +40 dBm, respectively, which are significantly higher than previously reported acoustic filters operating at similar frequencies.

The purpose of this work was to investigate the validity of Arrhenius accelerated-life testing when applied to gallium nitride (GaN) high electron mobility transistors (HEMT) lifetime assessments, where the standard assumption is that only critical stressor is temperature, which is derived from operating power, device channel-case, thermal resistance, and baseplate temperature. We found that power or temperature alone could not explain difference in observed degradation, and that accelerated life tests employed by industry can benefit by considering the impact of accelerating factors besides temperature. Specifically, we found that the voltage used to reach a desired power dissipation is important, and also that temperature acceleration alone or voltage alone (without much power dissipation) is insufficient to assess lifetime at operating conditions.

Reports to date of GaN HEMTs subjected to forward gate bias stress include varied extents of degradation. We report an extremely robust GaN HEMT technology that survived—contrary to conventional wisdom—high forward gate bias (+6 V) and current (>1.8 A/mm) for >17.5 hours exhibiting only a slight change in gate diode characteristic, little decrease in maximum drain current, with only a 0.1 V positive threshold voltage shift, and, remarkably, a persisting breakdown voltage exceeding 200 V.