Characteristics of dual δ -doped InGaPInGaAs pHEMTs with various doping profiles

Dual δ -doped InGaPInGaAs pseudomorphic high electron mobility transistors (pHEMTs) with various doping profile designs were adopted to investigate the relationship between the doping profile of pHEMTs and the surface phenomena. Compared to a single δ -doped pHEMT, the dual δ -doped design provided a high current density, which was suitable for low noise and high power applications [IEEE Trans. Electron Devices, 35, 879 (1988); J. Appl. Phys., 81, 3576 (1997)]. The influence of the δ -doped layer in GaAs Schottky diode parameters was studied [International Euroconference on Advanced Semiconductor Devices, pp. 391-394 (2000)]. The dual δ -doped and doped-channel InGaPInGaAs pHEMTs were also investigated and studied [IEEE Trans. Electron Devices, 54, 1617 (2007)]. However, the lower/upper δ -doped layer doping profile and surface phenomena of InGaPInGaAs pHEMTs are still ambiguous. In this work, the epitaxial concentration designs of lower and upper δ -doped layers were 1:3, 2:2, and 3:1 (unit: 1012 cm-2) for dual δ -doped InGaPInGaAs pHEMTs, respectively. The concentration profile of the lower and upper δ -doped layers can be adjusted to realize optimal InGaPInGaAs low noise and high linearity pHEMT.