Physical damage and damage removal on indium phosphide and gallium arsenide surfaces using low energy ions

Plasma-induced surface damage of III-V compound semiconductors is clarified with measurements of surface defect density induced by low energy ion bombardment of InP. InP (110) surfaces were prepared by cleavage of InP in ultrahigh vacuum, and then bombarded with He+ and Ar+ with energy in the range of 5 to 100 eV, and fluence in the range of 1012 to 1017 ions/cm2. Both He+ and Ar+ bombardment moved the Fermi levels of both n- and p-InP (110) surfaces towards 0.95 eV above the valence band maximum of InP. Ar+ caused more damage than He + when same bombardment energy was used. For the same type of ions, the density of surface defects induced by bombardment was increasing with both ion energy and fluence.;The removal of excessive surface state and plasma-damage from InP and GaAs (100) using low energy S+ was also studied. The S + bombardment resulted in formation of only In-S species on the InP surface, and Ga-S and As-S species on the GaAs surface. The surface Fermi levels for both sulfur ion-bombarded n and p-type samples of InP and GaAs were moved towards the mid-gap. Subsequent annealing removed the damage introduced during the ion bombardment and resulted in a (1 x 1) LEED pattern from both the InP and GaAs surfaces. After annealing at 400°C, the surface Fermi level of S+ treated n and p-type GaAs gave a separation larger than that of the UV/O3 and HF treated surfaces. The treatment was extended to repair Ar+ damaged InP surface. When InP samples were damaged by 200 eV Ar+ bombardment followed by 50 eV S+ treatment and annealing, we could obtain an InP surface with (1 x 1) LEED pattern and low surface states.;The ions with energy above 50 eV were more effective to form In-S and Ga-S species, which assisted the InP and GaAs surfaces in obtaining an ordered (1 x 1) structure upon annealing. Considering physical damage due to ion bombardment, we found that 50 eV is the optimal ion energy to form In-S and Ga-S species in the sulfur passivation of InP and GaAs.