A semiconductor structure includes: a channel layer; an active layer over the channel layer, wherein the active layer is configured to form a two-dimensional electron gas (2DEG) to be formed in the channel layer along an interface between the channel layer and the active layer; a gate electrode over a top surface of the active layer; and a source/drain electrode over the top surface of the active layer; wherein the active layer includes a first layer and a second layer sequentially disposed therein from the top surface to a bottom surface of the active layer, and the first layer possesses a higher aluminum (Al) atom concentration compared to the second layer. An HEMT structure and an associated method are also disclosed.

The present disclosure relates generally to structures in semiconductor devices and methods of forming the same. More particularly, the present disclosure relates to high electron mobility transistor (HEMT) devices having a silicided polysilicon layer. The present disclosure may provide an active region above a substrate, source and drain electrodes in contact with the active region, a gate above the active region, the gate being laterally between the source and drain electrodes, a polysilicon layer above the substrate, and a silicide layer on the polysilicon layer. The active region includes at least two material layers with different band gaps. The polysilicon layer may be configured as an electronic fuse, a resistor, or a diode.

A semiconductor device includes a transistor, a semiconductor layer, an active region and a conductive layer. The active region is in the semiconductor layer. The conductive layer is configured to maintain a channel in the active region when the transistor is triggered to be conducted.

In one embodiment, an impedance matching network includes a variable reactance circuit providing a variable capacitance or inductance. The variable reactance circuit includes reactance components and corresponding switching circuits. Each of the switching circuits includes a diode and a driver circuit to switch the diode. The driver circuit includes first and second switches coupled in series. A first driver is coupled to the first switch, a second driver is coupled to the second switch, and a third driver is coupled to the first and second drivers. The third driver provides a first signal to the first driver, and a second signal to the second driver. In providing the signals, the third driver increases and decreases a duration of a dead time between (a) driving the first driver on and the second driver off, or (b) driving the second driver on and the first driver off.

A high electron mobility transistor (HEMT) includes a carrier transit layer, a carrier supply layer, a main gate, a control gate, a source electrode and a drain electrode. The carrier transit layer is on a substrate. The carrier supply layer is on the carrier transit layer. The main gate and the control gate are on the carrier supply layer. The source electrode and the drain electrode are at two opposite sides of the main gate and the control gate, wherein the source electrode is electrically connected to the control gate by a metal interconnect. The present invention also provides a method of forming a high electron mobility transistor (HEMT).

Apparatus and circuits with dual polarization transistors and methods of fabricating the same are disclosed. In one example, a semiconductor structure is disclosed. The semiconductor structure includes: a substrate; an active layer that is formed over the substrate and comprises a first active portion having a first thickness and a second active portion having a second thickness; a first transistor comprising a first source region, a first drain region, and a first gate structure formed over the first active portion and between the first source region and the first drain region; and a second transistor comprising a second source region, a second drain region, and a second gate structure formed over the second active portion and between the second source region and the second drain region, wherein the first thickness is different from the second thickness.

A gallium nitride high electron mobility transistor including a substrate, a nucleation layer, a buffer layer, a channel layer, a barrier layer, a gate electrode, a source electrode, a drain electrode, and multiple first p-type gallium nitride islands is provided. A second side of the gate electrode is opposite to a first side of the gate electrode. The first p-type gallium nitride islands are respectively disposed between a first side of the drain electrode and the second side of the gate electrode, and the first p-type gallium nitride islands are electrically floating.

A control circuit applied in a specific element and including a first transistor and an electrostatic discharge (ESD) protection circuit is provided. The specific element has a III-V semiconductor material and includes a control electrode, a first electrode and a second electrode. The first transistor is coupled between the first electrode and the second electrode and has the III-V semiconductor material. The ESD protection circuit is coupled to the control electrode, the first transistor and the second electrode. In response to an ESD event, the ESD protection circuit provides a discharge path to release the ESD current from the control electrode to the second electrode.

A semiconductor device includes a compound semiconductor layer disposed on a substrate, a protection layer disposed on the compound semiconductor layer, and a source electrode, a drain electrode and a gate electrode penetrating the protection layer and on the compound semiconductor layer, wherein the gate electrode is disposed between the source electrode and the drain electrode. The semiconductor device also includes a plurality of field plates disposed over the protection layer and between the gate electrode and the drain electrode, wherein the plurality of field plates are separated from each other.

A method including forming a III-V compound layer on a substrate and implanting a main dopant in the III-V compound layer to form source and drain regions. The method further includes implanting a group V species into the source and drain regions. A semiconductor device including a substrate and a III-V compound layer over the substrate. The semiconductor device further includes source and drain regions in the III-V layer, wherein the source and drain regions comprises a first dopants and a second dopant, and the second dopant comprises a group V material.