The dislocation-related deep levels in InxGa1-xAs layers grown by molecular beam epitaxy on GaAs substrates have been investigated. Virtually unstrained InGaAs layers with mole fraction x of 0.10, 0.20, and 0.30 have been obtained by properly designing the In composition of linearly graded InxGa1-xAs buffers. Two electron traps, labeled as E-2 and E-3, whose activation energy scales well with the energy gap, have been found. Unlike E-2, E-3 shows: (i) a logarithmic dependence of the deep level transient spectroscopy amplitude on the filling pulse width and (ii) an increase of concentration as the buffer/InGaAs interface is approached. These findings, together with the observation that, in compressively strained In0.2Ga0.8As, the E-3-related concentration is definitely higher than that of virtually unstrained In0.2Ga0.8As, indicate that this trap is likely originated by extended defects like threading dislocations
Deep levels in virtually unstrained InGaAs layers deposited on GaAs
E Gombia;R Mosca;S Franchi
1998
Abstract
The dislocation-related deep levels in InxGa1-xAs layers grown by molecular beam epitaxy on GaAs substrates have been investigated. Virtually unstrained InGaAs layers with mole fraction x of 0.10, 0.20, and 0.30 have been obtained by properly designing the In composition of linearly graded InxGa1-xAs buffers. Two electron traps, labeled as E-2 and E-3, whose activation energy scales well with the energy gap, have been found. Unlike E-2, E-3 shows: (i) a logarithmic dependence of the deep level transient spectroscopy amplitude on the filling pulse width and (ii) an increase of concentration as the buffer/InGaAs interface is approached. These findings, together with the observation that, in compressively strained In0.2Ga0.8As, the E-3-related concentration is definitely higher than that of virtually unstrained In0.2Ga0.8As, indicate that this trap is likely originated by extended defects like threading dislocationsI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.