High transconductance AlGaN/GaN HEMT with thin barrier on Si(111) substrate

Abstract

The fabrication of high transconductance AlGa /Ga high electron mobility transistors (HEMTs) grown on high-resistivity silicon substrate is reported with an AlGa barrier thickness of only 12.5 nm. A maximum DC current density of 655 mA/mm, a current gain cutoff frequency (F T ) of 75 GHz and a power-gain cutoff frequency (F MAX ) of 125 GHz are obtained for a 0.125 µm gate length transistor. The device provides a record peak extrinsic transconductance of 332 mS/mm and an intrinsic value of 509 mS/mm. To the authors' knowledge, the obtained transconductances are the highest reported values from AlGa /Ga devices grown on a Si(111) substrate. This performance demonstrates the potential of Ga transistors on silicon for low-cost microwave power applications.

Al(Ga)N/GaN high electron mobility transistors on silicon

“…It results that a vertical soft BV of 420 V has been obtained on a HEMT with a total buffer thickness of less than 2.3 μm . Moreover, similar 2.5 μm thick structures have shown RF transmission losses of 0.4 dB mm −1 at 50 GHz that favorably compare with previously cited results . Another important point concerning the above‐mentioned approaches is that when the stress mitigating effect of intermediate layers or interlayers is sufficient, it is possible to grow relatively thick AlGaN buffer layers to enhance the confinement of the 2DEG in double heterostructure HEMTs (DH‐HEMTs).…”

Influence of AlN Growth Temperature on the Electrical Properties of Buffer Layers for GaN HEMTs on Silicon

“…Beyond trying to increase the resistivity by using lower growth temperatures, a complementary way to reduce RF propagation losses is to increase the resistive buffer layer thickness in order to reduce the capacitive coupling of the device with the lossy buried region. In such a way, Lecourt et al measured RF losses of 0.4 dB mm −1 at 50 GHz on a 2.5 μm thick structure grown by NH 3 ‐MBE on resistive ( ρ > 1 kΩ cm) Si(111) substrate . Figure shows propagation losses recorded for the thin buffer layers previously discussed, namely 0.5 μm GaN on 0.2 μm AlN nucleation layers grown at 830°C and 920°C, respectively.…”

Extraction of Packaged GaN Power Transistors Parasitics Using S-Parameters

“…According to Fig. 7, the real part of impedances 𝑍 12 𝑇 and 𝑍 22 𝑇 are given by ( 21) and ( 22) [16] : A relation linking 𝑅𝑒(𝑍 22 𝑇 ) to the gate voltage 𝑉 𝐺𝑆 is given by authors in [17]. In our study, it is proposed to generalize this relation to 𝑅𝑒(𝑍 12 𝑇 ).…”

“…In our study, it is proposed to generalize this relation to 𝑅𝑒(𝑍 12 𝑇 ). Therefore relations given by ( 23) and ( 24 Where 𝑉 𝑡 is the threshold voltage and 𝐾 1 , 𝐾 2 are constant coefficient depending on full channel conductance, threshold and built-in voltages [17].…”