Contribution of atomic and molecular ions to dry-etch damage

Using ions of low energy is accepted as an essential requirement in achievi ng low damage when dry-etching III-V semiconductors. SiCl4 is widely used t o make GaAs electron devices. We have studied the effect of a SiCl4 reactiv e ion etching environment as well as the effect of the bombardment by the s eparate constituent ions from a SiCl4 discharge in a low-energy implanter. Photoluminescence intensity measurements from GaAs/AlGaAs quantum well prob e structures have been used to study the damage inflicted. We find that mol ecular ions contribute less to deep damage than do atomic ions. Thus, low d amage may be promoted by selecting reactive etch chemistries with low ion e nergies and small atomic to molecular ion fractions. (C) 1999 American Inst itute of Physics. [S0003-6951(99)02028-8].