Vertical FET fabrication for optoelectronic integrated circuit

Abstract

The vertical GaAs FET (Field Effect Transisto) with a 3 $\mu{m}$ grating period was fabricated using two different epitaxy system, LPE and MOCVD. The VFET was designed to be used as a driving transistor for vertical OEIC (Optolelectronic Integrated Circuit) applications. Several simulations were performed to comprehend the mechanisms of VFET with KADES-II. The tungsten was used as the gate metal and the selective epitaxy method was used in fabrication. The device properties only using LPE system were not sufficient to drive the laser diode. However, The VFET by MOCVD had good D.C. characteristics and was operated in depletion mode. A maximum transconductance of 22mS/mm was achieved in the devices doped at $1\times10^{16}cm^{-3}$ The Schottky contacts between the overgrown layer and the tungsten gate sustained stable characteristics. The PBT (Permeable Base Transistor) or the SIT(Static Induction Transistor) can be fabricated by using the process sequences in this experiments.