OPTICAL PROPERTIES OF δ-DOPED GaAs AND GaAs/Al0.1Ga0.9As SUPERLATTICES

Radiative transition in δ-doped GaAs superlattices with and without Al_0.1Ga_0.9As barriers is investigated by using photoluminescence at low temperatures. The experimental results show that the transition mechanism of δ-doped superlattices is very different from that of ordinary superlattices. Emission intensity of the transition from the electron first excited state to hole states is obviously stronger than that from the electron ground state to hole states due to larger overlap integral between wavefunctions of electrons in the first excited state and hole states. Based on the effective mass theory we have calculated the self-consistent potentials, optical transition matrix elements and photoluminescence spectra for two different samples. By using this model we can explain the main optical characteristics measured. Moreover, after taking into account the bandgap renormalization energy, good agreement between experiment and theory is obtained.     

OPTICAL PROPERTIES OF δ-DOPED GaAs AND GaAs/Al0.1Ga0.9As SUPERLATTICES

Radiative transition in δ-doped GaAs superlattices with and without Al_0.1Ga_0.9As barriers is investigated by using photoluminescence at low temperatures. The experimental results show that the transition mechanism of δ-doped superlattices is very different from that of ordinary superlattices. Emission intensity of the transition from the electron first excited state to hole states is obviously stronger than that from the electron ground state to hole states due to larger overlap integral between wavefunctions of electrons in the first excited state and hole states. Based on the effective mass theory we have calculated the self-consistent potentials, optical transition matrix elements and photoluminescence spectra for two different samples. By using this model we can explain the main optical characteristics measured. Moreover, after taking into account the bandgap renormalization energy, good agreement between experiment and theory is obtained.     

一维二元非对角关联无序体系交流跳跃电导特性

在单电子紧束缚无序模型基础上，建立了一维二元非对角关联无序体系电子跳跃输运交流电导模型，并推导了其交流电导公式，通过计算其交流电导率，探讨了格点能量无序度、格点原子组分、非对角关联及温度、外场对体系交流跳跃电导的影响.计算结果表明，一维二元非对角关联无序体系的交流电导率随格点能量无序度的增大而减小.同时，体系中两种原子的组分的变化实际代表着体系成分无序程度的变化，因而对其交流电导率的影响很大，表现为随A类原子含量p的增加而先减小后增大.当引入非对角关联时，体系出现退局域化现象，电子波函数由局 关键词： 二元无序体系 交流跳跃电导 格点能量无序度 非对角关联     

PHOTOLUMINESCENCE STUDY OF GaAs/AlGaAs QUANTUM WELL HETEROSTRUCTURE INTERFACES

Photoluminescence (PL) ia used to study the interface properties of GaAs/AlGaAs quan-tum well (QW) heterostructures prepared by molecular beam epitaxy with growth interrup-tion (GI). The discrete luminescence lines observed for the sample with GI are assigned to the splitting of the heavy-hole exciton associated with heterointerface islands with the lateral size greater than excjton diameter and mean height less than one monolayer, and the spectra have the Gaussian lineshapes. The results strongly support the microroughness model. We also study the temperature dependence of the exciton energies and find that excitons are localized at the interface roughness at low temperature even in the sample with GI, The lateral size of the microroughness of the GI sample is estimated to be less than 5nm from the exciton localization energy.