Lattice distortion due to surface treatment of bias sputtering revealed by extremely asymmetric X-ray diffraction

Strain fields near InGaP or GaAs surfaces due to bias sputtering (Ar plasma-ion irradiation) for surface cleaning were measured by using a strain-sensitive X-ray diffraction technique. An extremely asymmetric InGaP or GaAs 1 1 3 reflection of the sample was measured to observe strain fields.We found that strain fields near InGaP or GaAs surfaces due to bias sputtering are affected by the bias voltage (Ar plasma-ion irradiation energy) used in this surface-cleaning treatment. By comparing measured 1 1 3 rocking curves and calculated ones based on the dynamical theory of X-rays, we estimated the thickness of a strained layer and a maximum strain at the surface. Resulting estimated parameters clearly show the bias sputtering to have two effects. One should be corresponding to the surface cleaning process of removing oxides on surfaces. The other is the lattice expansion, which is thought to be caused by compositional fluctuation near the surface or peening process of Ar ion. # 2004 Elsevier B.V. All rights reserved