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Improved quality non-polar III-nitride heteroepitaxial films and devices.

机译：改进质量的非极性III型氮化物异质外延薄膜和器件。

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摘要

GaN and its compounds suffer from polarization fields when grown along the c-⟨0001⟩ direction. These polarization fields result in poor carrier recombination efficiencies in quantum wells and shift in emission wavelength caused by the quantum confined stark effect due to spatial separation of the electron and hole wavefunction separation. It is possible to eliminate these effects by growing along one of the nonpolar directions, namely a-⟨11 20⟩ or m-⟨1100⟩, so that the polarization fields are normal to the growth direction. However films grown along these nonpolar directions suffer from high defect densities. Consequently, devices structures grown with these orientations suffer from poor electrical and optical characteristics.; In this dissertation these two issues were addressed so as to eliminate the polarization fields by nonpolar growth along the m-⟨11 00⟩ direction with metalorganic chemical vapor deposition (MOCVD) and to effectively reduce the high defect densities in films grown along the nonpolar directions employing a new growth technique, sidewall lateral epitaxial overgrowth (SLEO).; Previously, device-quality nonpolar a-⟨1120⟩ plane GaN films were achieved. Growth along this plane however was extremely sensitive to changes in growth conditions and was limited to low pressures and restricted precursor flows. In this dissertation it was shown that nonpolar m-⟨1100⟩ plane GaN films are more stable and less sensitive to changes in growth conditions. The first device-quality m-⟨1 100⟩ GaN films were then grown on m-plane 6H-SiC substrates with an AlN nucleation layer by MOCVD.; A new technique, SLEO, was developed to effectively reduce defect densities in nonpolar films. Using this method it is possible to reduce threading dislocation (TD) densities by 3-4 orders of magnitude to ∼106-10 7 cm-2 and stacking fault (SF) densities by 1-2 orders to ∼103-104 cm-1. This would improve the performance of devices subsequently grown on these high quality templates. For direct comparison, GaN/Al0.15GaN 360 nm UV LEDs were grown on co-loaded planar a-GaN, planar c-GaN and SLEO a-GaN templates. Devices grown on nonpolar SLEO films demonstrated ∼2-3x higher electron mobility, ∼3x lower series resistance, and ∼100-300x higher EQE when compared with the planar nonpolar films.
机译：GaN及其化合物沿c-〉0001〉方向生长时会受到极化场的影响。这些极化场导致量子阱中较差的载流子复合效率，并且由于电子的空间分离和空穴波函数分离而引起的由量子限制的斯塔克效应引起的发射波长的偏移。可以通过沿非极性方向之一（即a-〈11 20〉或m-〈1100〉）生长来消除这些影响，从而使偏振场垂直于生长方向。然而，沿这些非极性方向生长的膜具有高的缺陷密度。因此，以这些取向生长的器件结构遭受不良的电学和光学特性。本文讨论了这两个问题，以消除通过金属有机化学气相沉积（MOCVD）沿m-〈11 00〉方向非极性生长产生的极化场，并有效降低沿非极性方向生长的薄膜中的高缺陷密度采用一种新的生长技术，侧壁横向外延过度生长（SLEO）。以前，已经获得了器件质量的非极性a-〈1120〉平面GaN膜。然而，沿该平面的生长对生长条件的变化极为敏感，并且仅限于低压和受限的前体流动。本文表明，非极性m-〈1100〉面GaN薄膜更稳定，对生长条件的变化不敏感。然后，通过MOCVD法在具有AlN成核层的m平面6H-SiC衬底上生长第一器件质量的m-〈1100〉GaN薄膜。开发了一种新技术SLEO，可有效降低非极性薄膜中的缺陷密度。使用此方法可以将穿线错位（TD）密度降低3-4个数量级至〜106-10 7 cm-2，并将堆垛层错（SF）密度降低1-2个数量级至〜103-104 cm-1 。这将提高随后在这些高质量模板上生长的设备的性能。为了直接比较，在共载平面a-GaN，平面c-GaN和SLEO a-GaN模板上生长GaN / Al0.15GaN 360 nm UV LED。与平面非极性膜相比，在非极性SLEO膜上生长的器件显示出高约2-3倍的电子迁移率，低约3倍的串联电阻和高约100-300倍的EQE。

著录项

  • 作者

    Imer, Bilge.;

  • 作者单位

    University of California, Santa Barbara.;

  • 授予单位 University of California, Santa Barbara.;
  • 学科 Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2006
  • 页码 213 p.
  • 总页数 213
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 工程材料学;
  • 关键词

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