Al0.65Ga0.35N/Al0.4Ga0.6N Micro-Channel Heterojunction Field Effect Transistors With Current Density Over 900 mA/mm

Physica Rapid Research Ltrs

Talesara

et al. 2021

Self Cite

Enhancement‐mode ultrawide‐bandgap Al0.65Ga0.35N/Al0.4Ga0.6N metal–insulator–semiconductor heterojunction field‐effect transistors are demonstrated using fluorine‐plasma treatment for threshold voltage control and Al2O3 as gate dielectric. The device exhibits a threshold voltage of 5 V, a maximum drain current density of 105 mA mm−1, and a transconductance of 19 mS mm−1. In addition, the capability to achieve low off‐state current density at 3–4 × 10−9 mA mm−1, an exceptionally low gate leakage current density of 1.4 × 10−8 mA mm−1 even at a high forward gate bias of VGS = 12 V, and a current on/off ratio >1010 is shown. Small signal measurement shows that the device has a unity current gain cutoff frequency fT of 3.8 GHz and power gain cutoff frequency fmax of 4.5 GHz.

Section: Resultscontrasting

confidence: 61%

Section: Introductionmentioning

confidence: 99%

High‐Current‐Density Enhancement‐Mode Ultrawide‐Bandgap AlGaN Channel Metal–Insulator–Semiconductor Heterojunction Field‐Effect Transistors with a Threshold Voltage of 5 V

Han

Physica Rapid Research Ltrs

Talesara

et al. 2021

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“…UWBG Al x Ga 1−x N layers have higher breakdown field [17][18][19] which leads to a higher Baliga figure of merit. 20,21) Devices with channel alloy compositions of 40% or higher have been reported, [22][23][24][25][26] with currents as high as 1.3 A mm −1 . 27) Recently using fluorine treatment, Klein et al reported E-mode UWBG Al 0.7 Ga 0.3 N channel HFET with V TH = +0.5 V (at I DS = 0.1 mA mm −1 ) with a peak current of only 35 mA mm −1 (at V G = +6.6V).…”

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confidence: 99%

High-current recessed gate enhancement-mode ultrawide bandgap Al _x Ga_1−xN channel MOSHFET with drain current 0.48 A mm⁻¹ and threshold voltage +3.6 V

Mollah

Mamun

et al. 2021

Appl. Phys. Express

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We report a recessed-gate enhancement-mode Al2O3-ZrO2/Al0.6Ga0.4N/Al0.4Ga0.6N metal-oxide-semiconductor heterostructure field-effect transistor (MOSHFET) with drain current as high as 0.48 A mm−1 at a gate-source voltage of +12 V. This was enabled by a pseudomorphic HFET structure with graded back barrier for strain management and to screen the growth interface from the channel. The device exhibited a threshold-voltage (V TH) of 2.75 ± 0.57 V with absolute maximum V TH = 3.6 V, a +12.2 V shift from that for a depletion-mode MOSHFET fabricated on the same wafer. A 3-terminal breakdown voltage of 700 V was measured in the off-state, showing the viability of E-mode UWBG AlGaN for power electronics.

“…For a 1:6 (fill factor), a 100 nm long gate in a 1.6 μm long access region, a peak drain-current of 900 mA mm −1 was measured at a gate voltage of +2 V (Schottky gate). 21) The processing sequence for fabricating these micro-channel devices was complicated with several steps needing precise e-beam lithography. Moreover, high gate leakage in these HFET devices limits usage of positive gate bias and it also reduces the breakdown voltage.…”

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confidence: 99%

“…1(b)] which was shown to significantly reduce source and drain access resistances. 21,23) In this design, the device channel consists of relatively narrow 2DEG sections ("straits") separated by current blocking islands. Very high 2DEG concentration enables strong current spreading from the channel straits into the S-G and G-D regions.…”

mentioning

confidence: 99%

Ultrawide bandgap Al _x Ga_1–xN channel heterostructure field transistors with drain currents exceeding 1.3 A mm⁻¹

Gaevski

Mollah

et al. 2020

Appl. Phys. Express

Self Cite

We report an Ultrawide Bandgap Al0.4Ga0.6N channel metal-oxide-semiconductor heterostructure field effect transistor with drain currents exceeding 1.33 A mm−1 (pulse) and 1.17 A mm−1 (DC), around a 2-fold increase over past reports. This increase was achieved by incorporating a hybrid barrier layer consisting of an AlN spacer, n-doped Al0.6Ga0.4N barrier and a thin reverse graded AlxGa1–xN (x from 0.60 to 0.30) cap layer. To enhance current spreading, a “perforated” channel layout comprising of narrow channel sections separated by current blocking islands was used. A composite ALD deposited ZrO2/Al2O3 film was used as gate dielectric. A breakdown field above 2 MV cm−1 was measured.