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

We describe our research on the fabrication of GaInAsP/InP Light Emitting Diodes (LEDs) / Laser Diodes (LDs) at wavelength of 1.5 μm using wafer grown by Liquid Phase Epitaxy (LPE) system. The source materials (In, InP, GaAs and InAs and doping of In-Te and In-Zn) are baked at temperature of 610 °C at the horizontal LPE system. The epitaxially layers are formed on (100) InP substrate in the graphite boat with the cooling rate of 0.7 °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 metallization, annealing and lapping processes. About 20-30 LED chips (100 μm x 300 μm) can be obtained from a (8 mm x 10 mm) wafer. Characterization has been conducted to examine the LED basics characteristics which showing the diode characteristics of the chips at its voltage -current (V-i) curve. Furthermore, electroluminescence process is conducted by giving an instantaneous current pulse (100-400 ns, 1 KHz) on the chip and detecting the output light using Ge detector; resulting a voltage - time (V-t) 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 λ ∼ 1.5 μm 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 photolitography and etching techniques of LPE grown wafers is conducted.