Etching of n-type GaAs for fabrication of semiconductor laser

Formation of smooth-vertical mirrors on GaAs by wet etching and reactive ion etching has been investigated for the fabrication of oxide-isolated stripe geometry lasers. The wet etching was carried out by the solution H₂SO₄-H₂O₂-H ₂O at 2°C for 10 and 20 minutes. The dry etching was performed using SiCl₄ gas in a single chamber reactive ion etcher (RIE). The optimum values obtained for the RIE system to achieve a smooth and vertical profile were 25 mTorr, 25 seem and 50 W respectively for pressure of the etch gas, mass flow rate of the etch gas and power of the machine. The etch profiles obtained for both wet and dry etching were inspected in the scanning electron microscope (SEM). The etch rate for wet chemical etching was found 0.01 μm/minute while it was 0.45 μm/minute for dry etching