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 semiconductor device includes a buffer layer, a channel layer, and a carrier supply layer; first and second recesses formed in the channel layer and the carrier supply layer, to reach the buffer layer; first and second nitride semiconductor layers in the first and second recess, respectively; a source electrode over the first nitride semiconductor layer; a drain electrode over the second nitride semiconductor layer; and a gate electrode over the carrier supply layer between the first and second recesses. Each of the first and second nitride semiconductor layers includes first and second regions containing donors. An interface between the first and second regions is positioned deeper than two-dimensional electron gas on a surface side of the channel layer, and energy at a bottom of a conduction band of the second region is higher than energy at a bottom of a conduction band of the first region.

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.

A nitride semiconductor element capable of accommodating GaN electron transfer layers of a wide range of thickness, so as to allow greater freedom of device design, and a nitride semiconductor element package with excellent voltage tolerance performance and reliability. On a substrate, a buffer layer including an AlN layer, a first AlGaN layer and a second AlGaN layer is formed. On the buffer layer, an element action layer including a GaN electron transfer layer and an AlGaN electron supply layer is formed. Thus, an HEMT element is constituted.

A disclosed compound semiconductor device includes a substrate, a channel layer formed over the substrate, an electron supply layer famed on the channel layer, a first cap layer and a second cap layer formed at a distance from each other on the electron supply layer, a source electrode formed on the first cap layer, a drain electrode formed on the second cap layer, and a gate electrode formed on the electron supply layer between the first cap layer and the second cap layer. Each of the first cap layer and the second cap layer is a stacked film formed by alternately stacking i-type first compound semiconductor layers and n-type second compound semiconductor layers having a wider bandgap than the first compound semiconductor layers.

A method for manufacturing a HEMT transistor comprising the steps of: providing a wafer comprising a semiconductor body including a heterojunction structure formed by semiconductor materials that include elements of Groups III-V of the Periodic Table, and a dielectric layer on the semiconductor body; etching selective portions of the wafer, thus exposing a portion of the heterojunction structure; forming an interface layer by a surface reconstruction process, of a semiconductor compound formed by elements of Groups III-V of the Periodic Table, in the exposed portion of the heterojunction structure; and forming a gate electrode, including a gate dielectric and a gate conductive region, on said interface layer.

A semiconductor device includes an indium gallium nitride layer over an active layer. The semiconductor device further includes an annealed region beneath the indium gallium nitride layer, the annealed region comprising indium atoms driven from the indium gallium nitride layer into the active layer.

A compound semiconductor device includes a compound semiconductor layer, a gate electrode disposed above the compound semiconductor layer, and source and drain electrodes disposed above the compound semiconductor layer with the gate electrode between the source and drain electrodes, wherein the compound semiconductor layer has a groove in a surface thereof at least between the source electrode and the gate electrode in a region between the source electrode and the drain electrode, the groove gradually deepened toward the source electrode.

According to one embodiment, a semiconductor device includes a first semiconductor layer including a nitride semiconductor, a first electrode separated from the first semiconductor layer in a first direction, and a first insulating film including silicon and oxygen and being provided between the first semiconductor layer and the first electrode. The first insulating film has a first thickness in the first direction. The first insulating film includes a first position, and a distance between the first position and the first semiconductor layer is of the first thickness. A first hydrogen concentration of hydrogen at the first position is 2.510.sup.19 atoms/cm.sup.3 or less.

A nitride semiconductor element capable of accommodating GaN electron transfer layers of a wide range of thickness, so as to allow greater freedom of device design, and a nitride semiconductor element package with excellent voltage tolerance performance and reliability. On a substrate, a buffer layer including an AlN layer, a first AlGaN layer and a second AlGaN layer is formed. On the buffer layer, an element action layer including a GaN electron transfer layer and an AlGaN electron supply layer is formed. Thus, an HEMT element is constituted.