A method of forming a compound semiconductor substrate includes providing a crystalline base substrate having a first semiconductor material and a main surface, and forming a first semiconductor layer on the main surface and having a pair of tracks disposed on either side of active device regions. The first semiconductor layer is formed from a second semiconductor material having a different coefficient of thermal expansion than the first semiconductor material. The pair of tracks have a relatively weaker crystalline structure than the active device regions. The method further includes thermally cycling the base substrate and the first semiconductor layer such that the first semiconductor layer expands and contracts at a different rate than the base substrate. The pair of tracks physically decouple adjacent ones of the active device regions during the thermal cycling.

A method of fabricating a multi-layer epitaxial buffer layer stack for transistors includes depositing a buffer stack on a substrate. A first voided Group IIIA-N layer is deposited on the substrate, and a first essentially void-free Group IIIA-N layer is then deposited on the first voided Group IIIA-N layer. A first high roughness Group IIIA-N layer is deposited on the first essentially void-free Group IIIA-N layer, and a first essentially smooth Group IIIA-N layer is deposited on the first high roughness Group IIIA-N layer. At least one Group IIIA-N surface layer is then deposited on the first essentially smooth Group IIIA-N layer.

A semiconductor device includes a first semiconductor layer formed on a substrate; a second semiconductor layer and a third semiconductor layer formed on the first semiconductor layer; a fourth semiconductor layer formed on the third semiconductor layer; a gate electrode formed on the fourth semiconductor layer; and a source electrode and a drain electrode formed in contact with the second semiconductor layer. The third semiconductor layer and the fourth semiconductor layer are formed in an area immediately below the gate electrode, the fourth semiconductor layer is formed with a p-type semiconductor material, and the second semiconductor layer and the third semiconductor layer are formed with AlGaN, and the third semiconductor layer has a lower composition ratio of Al than that of the second semiconductor layer.

A CMOS device includes a PMOS transistor with a first quantum well structure and an NMOS device with a second quantum well structure. The PMOS and NMOS transistors are formed on a substrate.

Techniques are disclosed for providing a low resistance self-aligned contacts to devices formed in a semiconductor heterostructure. The techniques can be used, for example, for forming contacts to the gate, source and drain regions of a quantum well transistor fabricated in III-V and SiGe/Ge material systems. Unlike conventional contact process flows which result in a relatively large space between the source/drain contacts to gate, the resulting source and drain contacts provided by the techniques described herein are self-aligned, in that each contact is aligned to the gate electrode and isolated therefrom via spacer material.

A crystalline base substrate including a first semiconductor material and having a main surface is provided. The base substrate is processed so as to damage a lattice structure of the base substrate in a first region that extends to the main surface without damaging a lattice structure of the base substrate in second regions that are adjacent to the first region. A first semiconductor layer of a second semiconductor material is formed on a portion of the main surface that includes the first and second regions. A third region of the first semiconductor layer covers the first region of the base substrate, and a fourth region of the first semiconductor layer covers the second region of the base substrate. The third region has a crystalline structure that is disorganized relative to a crystalline structure of the fourth region. The first and second semiconductor materials have different coefficients of thermal expansion.

In an embodiment, a substrate structure includes a support substrate, a buffer structure arranged on the support substrate, the buffer structure including an intentionally doped superlattice laminate, an unintentionally doped first Group III nitride layer arranged on the buffer structure, a second Group III nitride layer arranged on the first Group III nitride layer forming a heterojunction therebetween, and a blocking layer arranged between the heterojunction and the buffer structure. The blocking layer is configured to block charges from entering the buffer structure.

The present invention provides a method for forming a quantum well device having high mobility and high breakdown voltage with enhanced performance and reliability. A method for fabrication of a Vertical Cylindrical GaN Quantum Well Power Transistor for high power application is disclosed. Compared with the prior art, the method of forming a quantum well device disclosed in the present invention has the beneficial effects of high mobility and high breakdown voltage with better performance and reliability.

A semiconductor device includes a first semiconductor layer formed on a substrate; a second semiconductor layer and a third semiconductor layer formed on the first semiconductor layer; a fourth semiconductor layer formed on the third semiconductor layer; a gate electrode formed on the fourth semiconductor layer; and a source electrode and a drain electrode formed in contact with the second semiconductor layer. The third semiconductor layer and the fourth semiconductor layer are formed in an area immediately below the gate electrode, the fourth semiconductor layer is formed with a p-type semiconductor material, and the second semiconductor layer and the third semiconductor layer are formed with AlGaN, and the third semiconductor layer has a lower composition ratio of Al than that of the second semiconductor layer.

A method includes providing a heterostructure body with a buffer region, and a barrier region disposed on the buffer region, and forming a gate structure for controlling the channel on the heterostructure body, the gate structure having a doped semiconductor region disposed on the heterostructure body, an interlayer disposed on the doped semiconductor region, and a gate electrode disposed on the interlayer. Forming the gate structure includes controlling a doping concentration of the doped semiconductor region such that a portion of the channel adjacent the gate structure is non-conductive at zero gate bias, and controlling electrical and geometrical characteristics of the interlayer based upon a relationship between the electrical and geometrical characteristics of the interlayer and corresponding effects on a static threshold voltage and a dynamic threshold voltage shift of the semiconductor device.