Integration of FETs and diodes using selective-area epitaxy

Abstract

In this work, A new fabrication technology that integrates simultaneously both FETs and diodes on a wafer using selective-area metalorganic chemical vapor deposition (SMOCVD) was proposed. Because this approach involves epitaxial growth, it is more advantageous than the implantation method, which is one of the effective method for integrating FETs and diodes, for increasing the thickness and doping concentration of the $n^{+}$-doped contact layer. In this paper, the structure of FECFET was used for the integration of FETs and diodes. Because the effective channel length (the distance between drain and source) of FECFET is very short, the knee voltage and transconductance of FECFET are superior to those of conventional MESFET with the same gate length, and especially, FECFET has the $n^{+}$ -doped contact layer under the active layer, it is easy to integrate with high quality diode with low series resistance. In this paper, to demonstrate the integration of FECFET and diode, two kinds of ICs consisted of diodes and FECFETs were selected. They are diode mixer & FECFET-IF amplifier and FECFET voltage controlled oscillator(VCO). First, diodes for mixer are measured. Diodes with the area of 1×30μ㎡ typically exhibited a zero-bias junction capacitance between 50fF and 80fF and series resistance was smaller than 8Ω, but, some diodes had very low series resistance less than 1-2 Ω. In this case, the series resistance is much less than that of selective deep implantation technology. The LO frequency and RF frequency of mixer were 35GHz and 36GHz, respectively. The diode mixer showed the conversion loss less than 7dB at 12dBm LO power. This measured value is the total conversion loss including the loss of the test fixture. Thus, the net conversion loss is expected to be less than this value. The gain of FECFET IF amplifieris exhibited about 5dB at the IF frequency of 1GHz. This value was less than the conversion loss (7dB) of diode mixer, and the center frequency was 0.7G...