Tunnel-injection quantum dot deep-ultraviolet light-emitting diodes with polarization-induced doping in III-nitride heterostructures
Tunnel-injection quantum dot deep-ultraviolet light-emitting diodes with polarization-induced doping in III-nitride heterostructures
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DOI：
10.1063/1.4862064
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发表时间：
2014-01
影响因子：
4
通讯作者：
J. Verma;S. Islam;V. Protasenko;P. Kandaswamy;H. Xing;D. Jena
中科院分区：
文献类型：
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作者：
J. Verma;S. Islam;V. Protasenko;P. Kandaswamy;H. Xing;D. Jena
在深紫外光谱窗口中的高效半导体光发射器遇到了半导体物理学中一些最根深蒂固的问题。在III族氮化物异质结构中，获得短波长光子发射需要使用宽带隙高Al组分AlGaN有源区。具有更高带隙的高导电性电子（n-）和空穴（p-）注入层对于电载流子注入是必要的。这种方法需要在非常宽的带隙半导体中激活非常深的掺杂剂，这是一项困难的任务。在这项工作中，提出了一种方法，并通过实验证明，以应对挑战。异质结构发光二极管的有源区使用超小外延生长的GaN量子点。值得注意的是，由于量子点中的极端量子限制，GaN的光发射能量从365 nm（3.4 eV，体带隙）被推到240 nm（> 5.2 eV）以下。这是可能的，因为在GaN/AlN系统中的特殊能带结构和能带排列。这种有源区设计至关重要地实现了两项进一步的创新，以实现高效的载流子注入：载流子的隧道注入和极化诱导p型掺杂。这三项进展的结合导致了深紫外发光二极管电致发光的重大提升，并为电泵浦短波长激光器奠定了基础。
Efficient semiconductor optical emitters in the deep-ultraviolet spectral window are encountering some of the most deep rooted problems of semiconductor physics. In III-Nitride heterostructures, obtaining short-wavelength photon emission requires the use of wide bandgap high Al composition AlGaN active regions. High conductivity electron (n-) and hole (p-) injection layers of even higher bandgaps are necessary for electrical carrier injection. This approach requires the activation of very deep dopants in very wide bandgap semiconductors, which is a difficult task. In this work, an approach is proposed and experimentally demonstrated to counter the challenges. The active region of the heterostructure light emitting diode uses ultrasmall epitaxially grown GaN quantum dots. Remarkably, the optical emission energy from GaN is pushed from 365 nm (3.4 eV, the bulk bandgap) to below 240 nm (>5.2 eV) because of extreme quantum confinement in the dots. This is possible because of the peculiar bandstructure and band alignments in the GaN/AlN system. This active region design crucially enables two further innovations for efficient carrier injection: Tunnel injection of carriers and polarization-induced p-type doping. The combination of these three advances results in major boosts in electroluminescence in deep-ultraviolet light emitting diodes and lays the groundwork for electrically pumped short-wavelength lasers.