Quantum semiconductor memory device including quantum dots
AssigneeFujitsu Limited
InventorsYoshihiro Sugiyama, Yoshiaki Nakata
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Abstract
A quantum semiconductor memory device includes a quantum structure formed on a substrate, wherein the quantum structure includes a plurality of self-organized quantum dots forming a strained heteroepitaxial system with respect to the substrate and an accumulation layer formed adjacent to the self-organized quantum dots, and wherein the self-organized quantum dots are formed of a semiconductor crystal having a composition set such that quantum levels of the self-organized quantum dots are located higher than a conduction band of the accumulation layer.
Claims20
A quantum semiconductor device, comprising:
- a semiconductor substrate;
- an undoped active layer formed on said semiconductor substrate, said active layer including a quantum structure;
- and
- an accumulation layer provided on said semiconductor substrate adjacent to said active layer, said quantum structure including:
- an undoped barrier layer of a first semiconductor crystal having a first lattice constant and a first bandgap;
- and
- a plurality of self-organized quantum dots each formed of a second semiconductor crystal having a second lattice constant different from said first lattice constant and a second bandgap smaller than said first bandgap, said second semiconductor crystal forming a strained heteroepitaxial system to said first semiconductor crystal, said plurality of self-organized quantum dots having respective quantum levels, and said second semiconductor crystal having a composition set such that said quantum level of said self-organized quantum dots are located higher than a conduction band edge of said accumulation layer.
A quantum semiconductor memory device, comprising:
- a semiconductor substrate;
- an active layer formed on said semiconductor substrate, said active layer including a quantum structure;
- an accumulation layer provided on said semiconductor substrate adjacent to said active layer, said quantum structure including:
- a barrier layer of a first semiconductor crystal having a first lattice constant and a first bandgap;
- and
- a plurality of self-organized quantum dots each formed of a second semiconductor crystal having a second lattice constant different from said first lattice constant and a second bandgap smaller than said first bandgap, said second semiconductor crystal forming a strained heteroepitaxial system to said first semiconductor crystal, said plurality of self-organized quantum dots having respective quantum levels;
- a first optical source emitting a first optical beam with a first wavelength set so as to cause a resonant excitation of an electron in said self-organized quantum dot from a ground quantum level for holes to a ground quantum level for electrons;
- and
- a second optical source for emitting a second optical beam with a second wavelength set so as to excite an electron in said ground quantum level for electrons to an energy level exceeding a bottom edge of a conduction band of said barrier layer.
Dependencies are inferred from the claim text.