Gate Orientation Dependence of InGaAs/AlGaAs High Electron Mobility Transistors Formed by Wet Recess Etching

Abstract

The gate orientation dependence of InGaAs/AlGaAs high electron mobility transistors (HEMTs) formed by the wet-chemical recess etching has been evaluated. The short channel effect strongly depends on the gate orientation and is significant in the order of [011], [001] and [011] oriented devices. Such orientation dependence results from a difference of the side-etching lengths, which are 0.01 µm, 0.03 µm and 0.06 µm for the [011], [001] and [011] oriented devices, respectively. The other characteristics of HEMTs such BV gd, gm and f T also depend on the gate orientation because of a difference of the recessed shape.

Comparative Study of DC and Microwave Characteristics of 0.12 µm Double-Recessed Gate AlGaAs/InGaAs/GaAs Pseudomorphic High-Electron-Mobility Transistors Using Dielectric-Assisted Process

“…As the side-etching length is increased, BV gd increases due to a reduction of the maximum electric field strength at the drain side, whereas g m decreases due to an increase in the source resistance. 18) The side-etching length of sample B obtained using as below wet recess etching is larger than that of sample A obtained using dry recess etching. This is because the wet chemical etches the GaAs cap layer isotropically, resulting in a lateral undercut, whereas anisotropic ECR maintains the GaAs cap layer opening dimension in the photoresist.…”

“…3 and 4, as the side-etching length is decreased, the depletion region becomes thin, the threshold voltage shifts towards the negative direction, and the short-channel effect becomes large. 18) Gate-to-drain breakdown voltage BV gd measurements were performed on the samples. The gate-to-drain breakdown voltage curves are shown in Fig.…”

Comparative Study of DC and Microwave Characteristics of 0.12 μm T-Shaped Gate AlGaAs/InGaAs/GaAs PHEMTs Using a Hybrid and Conventional E-beam Lithography Process

“…The breakdown voltage of the hybrid process is larger than that of the conventional process. It is believed that the side-etching length of the hybrid process is larger than that of the conventional process [4].…”

Fabrication and characteristics of 0.12 µm AlGaAs/InGaAs/GaAs pseudomorphic HEMT using a silicon nitride assisted process

“…By summarizing the above data from the viewpoint of the side-etching length, it is clear that there exists a trade-off between g m and BV gd . As the sideetching length is increased, BV gd increases due to a reduction of the maximum electric field strength at the drain side, while g m decreases due to an increase of the source resistance [16].…”

“…Since the distance between the footprint of the gate electrode and GaAs cap layer decreases by reducing the side-etching length, the fringe gate capacitance increases and thus f T degrades. The increase of the side-etching length results in an increment of f T in spite of the decrease of g m [16]. This is expected to lead to lower parasitic gate capacitances.…”