Study of damage induced by room-temperature Al ion implantation in Hg_0.8Cd_0.2Te by x-ray diffuse scattering

Ion-implantation is a widely used doping technique in II-VI semiconductors. Nevertheless, ion-implantation damage has to be better understood to properly control this process. In order to investigate the implantation-induced defects in such compounds, room-temperature implantations of 320 keV Al ions have been performed on crystalline samples of [111] Hg_1-xCd_xTe (x≈20%) for doses ranging from 10¹³ to 10¹⁵ cm^-2. We report the first measurements of x-ray diffuse scattering close to different Bragg reflections on such as-implanted samples. The evolution of the diffuse intensity as a function of the dose has been observed. The defect-induced diffuse intensity arises mainly from interstitial dislocation loops. Nevertheless, vacancy loops are observed above 3 × 10¹⁴ Al/cm². The mean radius of the dislocation loops increases in size by three to four times when the dose rises from 10¹³ to 10¹⁵ cm^-2. Finally, the saturation of point defects has been observed independently of their clustering at about 5 × 10¹³ Al/cm², that is in the same range as the saturation dose of the sheet electron concentration.