Papers by Keyword: Carrier Dynamics

Abstract: The effects of measurement technique and measurement conditions (injection level, temperature) on the measured carrier lifetimes in n- 4H-SiC epilayers are investigated. For three optical measurement techniques, it is shown that the high and low injection lifetimes can vary dramatically. Differences in the lifetime for varying injection level and temperature are approached both experimentally and via carrier dynamics simulations, assuming Z1/Z2 as the dominant defect. Reasonable agreement between measured and calculated behavior is obtained, as is insight into the recombination kinetics associated with the lifetime limiting defect.

Abstract: We have fabricated GaInP/Er,O-codoped GaAs (GaAs:Er,O)/GaInP double heterostructure (DH) light-emitting diodes (LEDs) and successfully observed 1.5 µm electroluminescence (EL) due to an Er-2O center under forward bias at room temperature. Er excitation cross section by current injection decreased with increasing GaAs:Er,O active layer thickness, implying reduced diffusion length of injected carriers in the active layer. Carrier dynamics in GaAs:Er,O have also been investigated by means of a pump and probe reflection technique. Time-resolved reflectivity of GaAs:Er,O exhibited a characteristic dip after a steep decrease to negative in less than 10 ps. The analysis of the characteristic dip revealed short lifetime in range of ps for photoexcited carriers. The extremely short lifetime is quite coincident with the reduced diffusion length of injected carriers, and suggests that a trap induced by Er and O codoping would play an important role in dynamics of nonequilibrium carriers in GaAs:Er,O.

Abstract: InAs/GaAs quantum dots (QDs) with ordered structure, due to their peculiar properties, open new way to design novel semiconductor devices such as single-electron transistors or highly parallel computing architectures. The lateral quantum dot alignment achieved during the selfassembly process is not well understood heretofore. The reason is, that quantum structures areusually small and studied at low temperatures. Conversely, the Scanning near-field optical microscopy (SNOM) allows study nanometer details in the non-offensive manner, in the room temperature with high spatial and temporal resolution. The first results of near-field optical study on aligned QDs are presented.