Selective‐area growth and fabrication of recessed‐gate GaN MESFET using plasma‐assisted molecular beam epitaxy

For the first time, selective‐area growth (SAG) technique has been developed using plasma‐assisted molecular beam epitaxy (PAMBE), enabling fabrication of a recessed‐gate structure for the metal‐semiconductor field‐effect transistor (MESFET) without etching. On patterned SiO 2 samples, polycrystalline GaN and single crystal n + ‐GaN were observed to grow in the masked and unmasked regions, respectively. The regrown layers were analyzed using AFM. Ohmic contact formed on the n + ‐GaN exhibited a vastly improved contact resistivity of 1.8 × 10 –8 Ω cm 2 , giving rise to excellent device characteristics including a peak drain current of 360 mA/mm and a maximum transconductance of 46 mS/mm. The advantages of SAG were further investigated by comparing the dc characteristics of recessed‐gate and unrecessed MESFET. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)