Reactive chemical beam etching of InP inside a chemical beam epitaxial growth chamber using phosphorus trichloride

We have extended the capability and versatility of a chemical beam epitaxial (CBE) system by demonstrating reactive chemical beam etching (RCBE) of InP using phosphorus trichloride (PCl3) as the gaseous etching beam injected directly into the growth chamber. This permits instant switching from etching to growth (and vice versa) in the same run for the first time in CBE. We investigate RCBE of InP at various substrate temperatures between ∼400 and 580 °C, under different PCl3 fluences, and etching conditions. Excellent surface morphology was obtained at high temperatures (≳530–570 °C) and under an etching rate of ≲6 Å/s. We also found that upon addition of trimethylindium flow equivalent to a growth rate of 1 Å/s during RCBE a dramatic improvement in surface morphology was obtained even at a high net etching rate of 10 Å/s. The surface morphology obtained under such conditions is indistinguishable from that of the original substrate surface.