Hydrogen‐related defects in boron doped p‐type silicon

The interaction between hydrogen and irradiation‐induced defects in boron‐doped silicon has been investigated in search of a passivation procedure for intrinsic defects, applicable for the solar cell industry. Deep level transient spectroscopy (DLTS) and minority carrier transient spectroscopy (MCTS) have been applied for defect characterization of proton implanted p‐type Fz and Cz‐Si, with a boron concentration of 2x10 16 cm –3 and 4x10 14 cm –3 , respectively. MCTS reveals a dominant electron trap located 0.22 eV below the conduction band edge (E c ) which is commonly ascribed to a boron‐interstitial oxygen‐interstitial complex (B i O i ). DLTS reveals several hole traps at 0.09, 0.18, 0.25, 0.35, 0.46 and 0.52 eV above the valence band edge (E v ). The levels at 0.09, 0.18 and 0.35 eV are identified as the carbon‐interstitial carbon‐substitutional pair (C i C s ), the divacancy center (V 2 ) and the carbon‐interstitial oxygen‐interstitial pair (K‐center), while the levels located at 0.25 and 0.52 eV have previously been suggested to result from defect complexes containing hydrogen. After annealing at 100‐200 °C for 30 min the measurements show that the H(0.25) level increases in amplitude, while V 2 and the K‐center decrease in amplitude. Heat treatment at 125 °C leads to almost complete disappearance of V 2 and the K‐center in the Fz samples. The obtained results suggest that the loss of V 2 and the K‐center is due to interaction with H. A possible identification of the E v +0.2 5eV level will be discussed. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)