Thermal stability of InP-based high electron mobility transistor epitaxial wafers

Systematic annealing of the InP-based high electron mobility transistor (HEMT) structure was performed. The thermal stability of the sheet carrier concentration $(Ns)$ and its relation to fluorine contamination were investigated by using van der Pauw–Hall effect measurements, secondary ion mass spectroscopy (SIMS), and photoluminescence (PL) measurement. The $Ns$ decreased after annealing at 450 °C in nitrogen ambient, which was due to fluorine contamination of the carrier-supply layer (CSL). The PL spectra from the InGaAs channel reflected the $Ns$ reduction. In addition, the PL spectra from the Si delta-doped InAlAs CSL drastically changed in line shape as the fluorine concentration increased. Such changes of PL and $Ns$ were not observed in the samples after annealing at 350 °C, where the CSL was scarcely contaminated by fluorine. The series of PL characterization and Hall effect and SIMS measurements can effectively analyze how fluorine contamination affects the Ns in the InP-based HEMT structures.