Novel GaN-based double-channel p-heterostructure field-effect transistors with a p-GaN insertion layer

GaN-based p-channel heterostructure field-effect transistors(p-HFETs)face significant constraints on on-state currents compared with n-channel high electron mobility transistors.In this work,we propose a novel double heterostructure which introduces an additional p-GaN insertion layer into traditional p-HFETs.The impact of the device structure on the hole densities and valence band energies of both the upper and lower channels is analyzed by using Silvaco TACD simulations,including the thickness of the upper AlGaN layer and the doping impurities and concentration in the GaN buffer layer,as well as the thickness and Mg-doping concentration in the p-GaN insertion layer.With the help of the p-GaN insertion layer,the C-doping concentration in the GaN buffer layer can be reduced,while the density of the two-dimensional hole gas in the lower channel is enhanced at the same time.This work suggests that a double heterostructure with a p-GaN insertion layer is a better approach to improve p-HFETs compared with those devices with C-doped buffer layer alone.

Improved device performance of recessed-gate AlGaN/GaN HEMTs by using in-situ N_(2)O radical treatment

The N_(2)O radicals in-situ treatment on gate region has been employed to improve device performance of recessedgate Al Ga N/Ga N high-electron-mobility transistors(HEMTs).The samples after gate recess etching were treated by N_(2)O radicals without physical bombardment.After in-situ treatment(IST)processing,the gate leakage currents decreased by more than one order of magnitude compared to the sample without IST.The fabricated HEMTs with the IST process show a low reverse gate current of 10;A/mm,high on/off current ratio of 108,and high f_(T)×L_(g)of 13.44 GHz·μm.A transmission electron microscope(TEM)imaging illustrates an oxide layer with a thickness of 1.8 nm exists at the AlGaN surface.X-ray photoelectron spectroscopy(XPS)measurement shows that the content of the Al-O and Ga-O bonds elevated after IST,indicating that the Al-N and Ga-N bonds on the AlGaN surface were broken and meanwhile the Al-O and Ga-O bonds formed.The oxide formed by a chemical reaction between radicals and the surface of the AlGaN barrier layer is responsible for improved device characteristics.

High power-added-efficiency AlGaN/GaN HEMTs fabricated by atomic level controlled etching

An atomic-level controlled etching(ACE)technology is invstigated for the fabrication of recessed gate AlGaN/GaN high-electron-mobility transistors(HEMTs)with high power added efficiency.We compare the recessed gate HEMTs with conventional etching(CE)based chlorine,Cl_(2)-only ACE and BCl^(3)/Cl_(2)ACE,respectively.The mixed radicals of BCl_(3)/Cl_(2)were used as the active reactants in the step of chemical modification.For ensuring precise and controllable etching depth and low etching damage,the kinetic energy of argon ions was accurately controlled.These argon ions were used precisely to remove the chemical modified surface atomic layer.Compared to the HEMTs with CE,the characteristics of devices fabricated by ACE are significantly improved,which benefits from significant reduction of etching damage.For BCl_(3)/Cl_(2)ACE recessed HEMTs,the load pull test at 17 GHz shows a high power added efficiency(PAE)of 59.8%with an output power density of 1.6 W/mm at Vd=10 V,and a peak PAE of 44.8%with an output power density of 3.2 W/mm at Vd=20 V in a continuous-wave mode.