ALD Al2O3 passivated MBE-grown AlGaN∕GaN HEMTs on 6H-SiC

GaN-based Metal-Oxide-Semiconductor Devices

“…A variety of thin films can be deposited utilizing ALD deposition with high density and low impurity at a low deposition temperature. The Al 2 O 3 and HfO 2 dielectrics are common insulators grown using ALD system and have been applied in AlGaN/GaN MOS-HEMTs (Park et al, 2004;Ye et al, 2005;Wu et al, 2006;Kim et al, 2007;Medjdoub et al, 2007;Yue et al, 2008;Feng et al, 2009;Chang et al, 2009). The qualities of Al 2 O 3 films gauged by several important figures of merit including uniformity, defect density and stoichiometric ratio of the deposited films, are comparably better, when ALD is chosen over the other deposition methods such as sputtering and electron-beam deposition methods.…”

Влияние низкотемпературного надбарьерного слоя GaN на концентрацию электронов в гетероструктуре AlGaN/GaN

“…Неизбежное наличие в гетерострук-туре AlGaN/GaN активных поверхностных состояний ограничивает возможности устройств, приводя к эффек-ту коллапса тока, снижению пробойного напряжения между стоком и затвором, высоким токам утечки затво-ра [3][4][5]. Эффективным способом борьбы с негативны-ми поверхностными эффектами является формирование тонких пассивирующих слоев диэлектриков SiO 2 , Al 2 O 3 , Si 3 N 4 и других [6][7][8][9].…”

Recessed 70-nm Gate-Length AlGaN/GaN HEMTs Fabricated Using an $\hbox{Al}_{2}\hbox{O}_{3}/\hbox{SiN}_{x}$ Dielectric Layer

“…The device without the dielectric layer demonstrated an extrinsic maximum transconductance of 325 mS/mm at V gs of −3.9 V and a drain bias (V ds ) of 4 V. From the gate-bias intercept of the linear extrapolation of the drain-current curve at peak g m position, the threshold voltage was determined to be −4.9 V. For the device with dielectric layer, the extrinsic maximum transconductance was measured as 374 mS/mm at V ds = 4 V, and the threshold voltage was −5.2 V. The shift of the threshold voltage in the negative direction is also due to the increase of the carriers in the channel. The improvements in the dc characteristics demonstrated that the Al 2 O 3 /SiN x dielectric bilayer is an effective passivation layer [8]. The small-signal RF characteristics were measured using an Agilent 8510C network analyzer in the 1-40-GHz range.…”

“…In this process, it was possible to control each etch step independently. It should be noted that ALD Al 2 O 3 , much like plasma-enhanced CVD (PECVD) SiN x , possesses excellent passivation characteristics for AlGaN/GaN HEMTs [8].…”