N-polar GaN-based MIS-HEMTs for mixed signal applications
Dept. of Electr. & Comput. Eng., Univ. of California, Santa Barbara, CA, USADOI: 10.1109/MWSYM.2010.5518145 Conference: Microwave Symposium Digest (MTT), 2010 IEEE MTT-S International
Source: IEEE Xplore
GaN-based transistors are attractive for the next-generation RF power and mixed signal electronics due to their high breakdown field and high carrier saturation velocity. III-N high electron mobility transistors (HEMTs) fabricated on the N-face of GaN are well-suited to address the problems of poor electron confinement and high ohmic contact resistance in the highly scaled transistors. At 4 GHz, N-polar metal-insulator-semiconductor (MIS)-HEMTs with a gate length of 0.7 μm exhibited a highest output power density (Pout) of 8.1 W/mm and a highest power-added efficiency (PAE) of 71%, while a Pout of 4.2 W/mm and a PAE of 49% were achieved at 10 GHz. A high speed N-polar MIS-HEMT fabricated with a gate-first self-aligned InGaN-based ohmic contact regrowth technology was characterized, demonstrating an ultra-low contact resistance of 23 Ω-μm and a state-of-the-art fT·LG product of 16.8 GHz-μm with a gate length of 130 nm.
- [Show abstract] [Hide abstract]
ABSTRACT: An anomalous output conductance that resembled short-channel effects was observed in long-channel N-polar GaN-channel/AlGaN-back-barrier/GaN-buffer high electron mobility transistors. The phenomenon could not be reasonably explained by drain-induced barrier lowering, leakage currents, or impact ionization events. We propose that the output conductance was caused by the ionization of a donorlike hole trap state at the negatively polarized AlGaN-back-barrier/GaN-buffer interface that shifted the threshold voltage at the drain side of the gate, where a high-field depletion region developed beyond current saturation. No evidence of increased output conductance or related device performance degradation was apparent under small-signal high-frequency conditions. The output conductance was suppressed by introducing photogenerated holes that compensated the traps. The effect of several typical back-barrier designs on the dc output conductance was examined.IEEE Transactions on Electron Devices 11/2012; 59(11):2988-2995. DOI:10.1109/TED.2012.2211599 · 2.47 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: In this paper, we report the recent progress in the high-frequency performance of enhancement-mode devices in the novel N-polar GaN technology and provide a pathway for further scaling. The intrinsic advantages of electron confinement, polarization doping of the back-barrier and the absence of a source barrier in N-polar GaN technology were leveraged with polarization engineering with a top barrier for enhancement mode operation and advanced self-aligned source/drain technology for low parasitic access resistances. The scalability of the device structures are explored in terms of short-channel effects and high-frequency performance. Low-field electron mobility in vertically scaled channel was also investigated providing insights on the scattering mechanism.Semiconductor Science and Technology 06/2013; 28(7):074006. DOI:10.1088/0268-1242/28/7/074006 · 2.19 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.