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Control of photoexcited-carrier distribution through intersubband resonances in semiconductor superlattices

通过半导体超晶格中的子带间共振控制光激发载流子分布

基本信息

批准号：
11640322
负责人：
NAKAYAMA Masaaki
金额：
$ 2.18万
依托单位：
Osaka City University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

The purpose of this study is to clarify the mechanism which controls photoexcited-carrier distribution of high-order subbands and to pursue the possibility of intersubband light emission (mid-infrared region) in semiconductor superlattices (SLs). The samples used are GaAs/AlAs and GaAs/InAlAs SLs grown by molecular-beam epitaxy. The SL layers are embedded in p-i-n or n-i-n structure in order to apply a bias voltage (an electric field). The summary of the research results is as follows.(1) In the conduction band of a GaAs/AlAs SL, the GaAs and AlAs layers are the quantum wells for the Γ and X valleys, respectively ; therefore, we have focused on the resonance and scattering between the GaAs-Γ electron subband and AlAs-X one. We measured the interband and intersubband emissions under various bias voltages (electric fields) which control the energy spacing between the Γ and X subbands, and analyzed the experimental results. In a GaAs/AlAs double-QW SL [AlAs (5.7 nm)/GaAs (4.5 nm)/AlAs (1.1 nm)/GaAs (2.7 nm)] and a GaAs (15.3 nm)/AlAs (4.5 nm) SL, it is found that the Γ-X subband resonance and scattering causes the carrier distribution of the high-order Γ subbands. We have succeeded to detect the intersubband emission (electroluminescence) in a mid-infrared region under the above carrier-distribution condition.(2) In GaAs/InAlAs SLs, we have focused on the resonance and scattering between the heavy-hole (HH) and light-hole (LH) subbands, where the LH-subband energy is higher than the HH-subband one. The HH-LH resonance was confirmed by photocurrent-voltage characteristics in some samples. In a GaAs (3.7nm)/In_<0.3>Al_<0.7>As (0.85nm) SL, it is found from the interband emission properties under various bias voltages that the HH-LH resonance and scattering causes the carrier distribution of the LH subband, which results in appearance of the LH-related emission associated with disappearance of the HH-related emission.

本研究的目的是阐明控制高阶子带光激发载流子分布的机制，并探索半导体超晶格（SL）中子带间发光（中红外区域）的可能性。使用的样品是通过分子束外延生长的 GaAs/AlAs 和 GaAs/InAlAs SL。 SL 层嵌入 p-i-n 或 n-i-n 结构中，以便施加偏置电压（电场）。主要研究成果如下：(1)在GaAs/AlAs SL的导带中，GaAs层和AlAs层分别是γ谷和X谷的量子阱；因此，我们重点研究GaAs-Γ电子子带和AlAs-X电子子带之间的共振和散射。我们测量了控制 Γ 和 X 子带之间能量间隔的各种偏置电压（电场）下的带间和子带间发射，并对实验结果进行了分析。在GaAs/AlAs双QW SL [AlAs (5.7 nm)/GaAs (4.5 nm)/AlAs (1.1 nm)/GaAs (2.7 nm)]和GaAs (15.3 nm)/AlAs (4.5 nm) SL中，发现Γ-X子带共振和散射导致高阶Γ子带的载流子分布。我们成功地在上述载流子分布条件下检测到了中红外区域的子带间发射（电致发光）。（2）在GaAs/InAlAs SLs中，我们重点研究了重空穴（HH）和轻空穴（LH）子带之间的共振和散射，其中LH子带能量高于HH子带能量。 HH-LH 共振通过一些样品的光电流-电压特性得到证实。在GaAs(3.7nm)/In_<0.3>Al_<0.7>As(0.85nm)SL中，从不同偏置电压下的带间发射特性发现，HH-LH共振和散射导致LH子带的载流子分布，从而导致LH相关发射的出现与HH相关发射的消失相关。