Photoconductivity (PC) in near-infrared range and dDynamics of near-IR-excited photocurrent in metamorphic InAs/InxGa1-xAs quantum dot (QD) structures with x = 0.15 and 0.31 were studied. After the a fast increase of in photoconductivity (PC) at the excitation start, the sample with x = 0.15 revealed a monotonous degradation of PC under stable excitation of QD ground states and buffer band-to-band. The degradation dynamics was found to be well fitted by allometric exponent ~ exp[-(t/)] with different fitting parameters depending on the excitation energy. We attribute Tthe PC degradation under a stable excitation is proposed to be attributed to electron traps found near QDs by thermally stimulated current (TSC) spectroscopy. These traps, when being filled by electrons due to the sample illumination, are assumed to cause Coulomb screening of the Wwetting Llayer (WL) conductivity channel against the electrons realizing coming from the both the QDs and embedding InGaAs layers. OtherwiseOn the other hand, the PC degradation effect in the structure with x = 0.31 is found to be less pronounced, showing and superimposed by a long-term increase kinetics. This might be due to a higher density of traps near the QD layer, which was revealed by TSC study. A significant fraction of these traps is suggestedare found to be located not only around QDs and, therefore, these traps can lead to the usual deceleration of increase kinetics. At With such a distribution of defects, WL Coulomb screening of the wetting layer apparently is not as effective.
Deep Level Influence on Photoconductivity of Metamorphic InAs/InGaAs Quantum Dot Structures
Seravalli L;Trevisi G;Frigeri P;
2018
Abstract
Photoconductivity (PC) in near-infrared range and dDynamics of near-IR-excited photocurrent in metamorphic InAs/InxGa1-xAs quantum dot (QD) structures with x = 0.15 and 0.31 were studied. After the a fast increase of in photoconductivity (PC) at the excitation start, the sample with x = 0.15 revealed a monotonous degradation of PC under stable excitation of QD ground states and buffer band-to-band. The degradation dynamics was found to be well fitted by allometric exponent ~ exp[-(t/)] with different fitting parameters depending on the excitation energy. We attribute Tthe PC degradation under a stable excitation is proposed to be attributed to electron traps found near QDs by thermally stimulated current (TSC) spectroscopy. These traps, when being filled by electrons due to the sample illumination, are assumed to cause Coulomb screening of the Wwetting Llayer (WL) conductivity channel against the electrons realizing coming from the both the QDs and embedding InGaAs layers. OtherwiseOn the other hand, the PC degradation effect in the structure with x = 0.31 is found to be less pronounced, showing and superimposed by a long-term increase kinetics. This might be due to a higher density of traps near the QD layer, which was revealed by TSC study. A significant fraction of these traps is suggestedare found to be located not only around QDs and, therefore, these traps can lead to the usual deceleration of increase kinetics. At With such a distribution of defects, WL Coulomb screening of the wetting layer apparently is not as effective.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
