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Smaller antenna-gate gap for higher sensitivity of GaN/AlGaN HEMT terahertz detectors
摘要： We report an attempt to improve the sensitivity of terahertz detection based on self-mixing in antenna-coupled ?eld-effect transistors by enhancing the ?eld-effect factor and the antenna factor with a reduced gate length and a reduced antenna-gate gap, respectively. An optical noise equivalent power (NEP) of 3:7 pW= ??????Hz at 0.65 THz was achieved in a GaN/AlGaN high-electron-mobility transistor (HEMT) with a gate length of 300 nm and an antenna-gate gap of 200 nm at room temperature. It was found that the antenna factor was inversely proportional to the antenna-gate gap, and the responses upon coherent/incoherent terahertz irradiation were well described by the self-mixing model. To ?ll the NEP gap of 0:1 (cid:2) 1 pW= ??????Hz between room-temperature and cryogenic detectors by HEMT-based detectors at room temperature, impedance match needs to be carefully considered.
关键词： terahertz detection,GaN/AlGaN HEMT,self-mixing,field-effect transistors,antenna-coupled
更新于2025-09-23 15:19:57
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Terahertz intersubband absorption of GaN/AlGaN step quantum wells grown by MOVPE on Si(111) and Si(110) substrates
摘要： We demonstrate terahertz intersubband absorptions in nitride step quantum wells (SQWs) grown by metal organic vapor phase epitaxy simultaneously on two different substrate orientations [Si(111) and Si(110)]. The structure of the SQWs consists of a 3 nm thick Al0.1Ga0.9N barrier, a 3 nm thick GaN well, and an Al0.05Ga0.95N step barrier with various thicknesses. This structure design has been optimized to approach a ?atband potential in the wells to allow for an intersubband absorption in the terahertz frequency range and to maximize the optical dipole moment. Structural characterizations prove the high quality of the samples. Intersubband absorptions at frequencies of 5.6 THz (k (cid:2) 54 lm), 7 THz (43 lm), and 8.9 THz (34 lm) are observed at 77 K on both substrate orientations. The observed absorption frequencies are in excellent agreement with calculations accounting for the depolarization shift induced by the electron concentration in the wells.
关键词： Si(111),GaN/AlGaN,step quantum wells,intersubband absorption,Si(110),MOVPE,terahertz
更新于2025-09-12 10:27:22
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[IEEE 2019 Compound Semiconductor Week (CSW) - Nara, Japan (2019.5.19-2019.5.23)] 2019 Compound Semiconductor Week (CSW) - High Responsivity and Low Dark Current Ultraviolet Photodetectors Using p-GaN/AlGaN/GaN Heterostructure
摘要： This paper reports a p-GaN/AlGaN/GaN heterostructure photodetector (PD) with high responsivity and high photo-to-dark current ratio (Iph/Idark). Due to the inherent depletion of the 2-D electron gas in the heterostructure by the p-type GaN, the dark current of the PD is significantly suppressed without compromising the advantages of high photocurrent and responsivity in AlGaN/GaN heterostructure PDs. As a result, both a large responsivity of 2×104 A/W and a high Iph/Idark of 107 at a bias of 5 V were achieved in our device under UV light with a wavelength of 365 nm and intensity of 5 μW/mm2. Moreover, a large UV to visible rejection ratio of around 3000 was also observed in the device. The superior device performance in our work compared to other reported results suggests the great potential using the p-GaN/AlGaN/GaN heterostructure based PDs for high-sensitivity UV detection.
关键词： p-GaN,AlGaN/GaN heterostructure,UV photodectors
更新于2025-09-11 14:15:04