Fabrication of infrared LEDs/LDs at wavelength of 1.5 μm using LPE-grown wafer

Abstract

We describe our research on the fabrication of GaInAsP/InP Light Emitting Diodes (LEDs)/Laser Diodes (LDs) at wavelength of 1.5 micrometers using wafer grown by Liquid Phase Epitaxy (LPE) system. The source materials are baked at temperature of 610 degrees C at the horizontal LPE system. The epitaxially layers are formed on InP substrate in the graphite boat with the cooling rate of 0.7 degrees C/min. The wafers are characterized using Scanning Electron Microscope (SEM), Photoluminescence (PL) and x-ray Diffraction (XRD) techniques. It is formed into LED chips by cleaving method after metalization, annealing and lapping processes. About 20-30 LED chips can be obtained from a wafer. Characterization has been conducted to examine the LED basics characteristics which showing the diode characteristics of the chips at its voltage-current curve. Furthermore, electroluminescence process is conducted by giving an instantaneous current pulse on the chip and detecting the output light using Ge detector; resulting a voltage-time curve displayed at a digital storage oscilloscope. The spectrum of the LED chip was observed by using an optical spectrum analyzer, giving peak wavelength at (lambda) approximately 1.5 micrometers with spectral width between 90-105 nm. Future works in fabrication of GaInAsP/InP LD at this wavelength is still underway starting with preliminary experiment of photolithography and etching techniques of LPE grown wafers is conducted.