Electric-field-enhanced emission and annealing behaviour of electron traps introduced in n-Si by low-energy He ion bombardment

摘要

The isochronal annealing and electric-field-enhanced emissionproperties of three defects (EHe203 , EHe584 and EHe211), observed inlow-energy He-ion bombarded n-Si, were studied using deep leveltransient spectroscopy. EHe203 (Ec - 0.20 eV) and EHe584 (E_c - 0.58eV) were thermally stable up to ～400 ℃ after which their removalwas accompanied by the introduction of a secondary defect EHe211 (E_c- 0.21 eV). EHe211 was thermally stable at 650 ℃. The emission rateof EHe203 was significant for electric fields above 4 x 10~4 Vcm~(-1), and was enhanced by over 3 orders of magnitude for acorresponding three-fold increase in electric field. The emissionrate of EHe211 was only weakly field dependent over the electricfield range studied, while that of EHe584 remained constant forelectric fields between 3 x 10~4 and 9 x 10~4 V cm~(-1). EHe584 hasbeen proposed to be an acceptor-type defect. It was found that squarewells of radii 57 A and 40 A described the potentials induced byEHe203 and EHe211, respectively, reasonably well. Alternatively,Gaussian potential wells with α = 20 A and V_0 = 0.30 eV (EHe203)and α = 12 A and V_0 = 0.35 eV (EHe211) could be used to fit ourexperimental data.