Absrracf -A monolithically integrated p-i-n FET amplifier has been fabricated using ion-implanted indium phosphide (InP) JFET's. The vertically integrated material structure consists of a vapor phase epitaxy (VPE) grown InCaAs photoabsorption layer and a metal organic chemical vapor deposition (MOCVD) grown Fe-doped semi-insulating layer. A Zn diffusion was performed to complete the p-i-n photodiode. High-performance fully implanted InP JFET's were used to form the integrated amplifier with a symmetrical design to remove the dc offset. With a receiver sensitivity of ~ 36.4 dBm measured at 200-Mbit/s NRZ for IO RER, it is easily the most sensitive monolithic p-i-n FET preamp yet reported in this frequency range. The p-i-n amplifier has a dynamic range of 15 dH.
I. INTRODUC rioN HE OPTICAL communication systems developed in thisT decade use both short-(0.8-0.9 pm) and long-(1.3-1.6 pni) wavelength regions, but due to the lower attenuation transmission windows in silica fibers in the long-wavelength region. the GaInAsP alloy materials grown lattice matched to indium phosphide (InP) have drawn much attention. The InPbased optoelectronics integrated circuits (OEIC's), therefore, have become an important component for communication systems to be built in the future. In order to build such integrated circuits. one requires a good electronics technology. Unlike Si and GaAs, however, InP does not have a wellestablished FET technology. Due to gate-semiconductor interfacial problems, the metal-insulator-semiconductor (MIS) and metal-semiconductor (MES) FET's do not appear to be practical in InP. InP JFET's have demonstrated good performance and may be the device of choice until the problems with other options can be solved.Several groups have reported long-wavelength integrated p-i-n FET photodetector devices using InPiInGaAs FET's operating at various bit rates complete amplifier, including a level-shifting buffer stage. We report in this paper the fabrication and performance of an integrated p-i-n FET amplifier with high sensitivity. The amplifier is made using high-performance fully ion-implanted InP JFET's and, therefore, only materials grown lattice matched to an InP substrate are used. Fig. 1 shows schematically the structure of the integrated p-i-n JFET device. The material was grown on an nt-InP substrate in two steps. The first growth was done by chloride vapor phase epitaxy (VPE) [7]. Following the growth of an undoped InP buffer, a 3.5-pm-thick I%,ssGq 4 7 A~ layer with an electron concentration less than 1 x IOi5 cm ~ was grown and capped by another layer of undoped InP. The second growth was done by atmospheric pressure metal organic chemical vapor deposition (MOCVD) [8], [9] and resulted in a 3-pm-thick Fe doped semi-insulating InP layer with a typical resistivity higher than lo7 Cl.cm.
DEVICE STRUCTURE AND FABRICATIONThe wafer with grown epilayers was then subjected to a series of ion implantations to form the JFET. The details of the ion implantation and activation are similar to those reported earlier [lo...
