Abstract: An improved pseudomorphic high electron mobility transistor (pHEMT) and heterojunction bipolar transistor (HBT) integrated epitaxial structure, in which the structure comprises a substrate, a pHEMT structure, an etching-stop spacer layer, and an HBT structure. The pHEMT structure comprises a buffer layer, a bottom barrier layer, a first channel spacer layer, a channel layer, a second channel spacer layer, a Schottky spacer layer, a Schottky donor layer, a Schottky barrier layer, an etching-stop layer, and at least one cap layer. By introducing the first channel spacer layer and the second channel spacer layer to reduce the density of the dislocations and to reduce the compressive strain in the pseudomorphic channel layer.

Abstract: An improved pseudomorphic high electron mobility transistor (pHEMT) and heterojunction bipolar transistor (HBT) integrated epitaxial structure and the fabrication method thereof, in which the structure comprises a substrate, a pHEMT structure, an etching-stop spacer layer, and an HBT structure. The pHEMT's structure comprises a buffer layer, a barrier layer, a first channel spacer layer, a channel layer, a second channel spacer layer, a Schottky barrier layer, an etching-stop layer, and at least one cap layer. The fabrication method of an HBT and a pHEMT are also included.

Abstract: An oxidized low density lipoprotein sensing device for a gallium nitride process is a GaN HEMT device including: a gateless AlGaN/GaN sensing transistor device, a testing window, a source, a drain, two metal connecting wires and a passivation layer. The gateless AlGaN/GaN sensing transistor device has an epitaxial wafer structure including a GaN layer and an aluminum gallium nitride layer. The testing window is disposed on the epitaxial wafer structure. The metal connecting wire is disposed on a source and a drain. The passivation layer is covered onto a surface of the sensing device except the testing window. A built-in piezoelectric field is created by the properties of FET and the polarization effect of AlGaN/GaN to achieve the effect of sensing the level of oxidizing proteins in human body quickly, accurately and easily.