title: Thickness variations and absence of lateral compositional fluctuations in aberration-corrected STEM images of InGaN LED active regions at low dose.
abstract: Aberration-corrected scanning transmission electron microscopy images of the In(0.15)Ga(0.85)N active region of a blue light-emitting diode, acquired at ~0.1% of the electron dose known to cause electron beam damage, show no lateral compositional fluctuations, but do exhibit one to four atomic plane steps in the active layer's upper boundary. The area imaged was measured to be 2.9 nm thick using position averaged convergent beam electron diffraction, ensuring the sample was thin enough to capture compositional variation if it was present. A focused ion beam prepared sample with a very large thin area provides the possibility to directly observe large fluctuations in the active layer thickness that constrict the active layer at an average lateral length scale of 430 nm.
authors.affiliation: 1Department of Materials Science and Engineering,University of Wisconsin-Madison,Madison,WI 53706,USA.
authors.forename: Andrew B
authors.initials: AB
authors.lastname: Yankovich
authors.affiliation: 1Department of Materials Science and Engineering,University of Wisconsin-Madison,Madison,WI 53706,USA.
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Kvit
authors.affiliation: 2Department of Electrical and Computer Engineering,Virginia Commonwealth University,Richmond,VA 23284,USA.
authors.forename: Xing
authors.initials: X
authors.lastname: Li
authors.affiliation: 2Department of Electrical and Computer Engineering,Virginia Commonwealth University,Richmond,VA 23284,USA.
authors.forename: Fan
authors.initials: F
authors.lastname: Zhang
authors.affiliation: 2Department of Electrical and Computer Engineering,Virginia Commonwealth University,Richmond,VA 23284,USA.
authors.forename: Vitaliy
authors.initials: V
authors.lastname: Avrutin
authors.affiliation: 2Department of Electrical and Computer Engineering,Virginia Commonwealth University,Richmond,VA 23284,USA.
authors.forename: Huiyong
authors.initials: H
authors.lastname: Liu
authors.affiliation: 2Department of Electrical and Computer Engineering,Virginia Commonwealth University,Richmond,VA 23284,USA.
authors.forename: Natalia
authors.initials: N
authors.lastname: Izyumskaya
authors.affiliation: 2Department of Electrical and Computer Engineering,Virginia Commonwealth University,Richmond,VA 23284,USA.
authors.forename: Ümit
authors.initials: Ü
authors.lastname: Özgür
authors.affiliation: 3FEI Company,Hillsboro,OR 97124,USA.
authors.forename: Brandon
authors.initials: B
authors.lastname: Van Leer
authors.affiliation: 2Department of Electrical and Computer Engineering,Virginia Commonwealth University,Richmond,VA 23284,USA.
authors.forename: Hadis
authors.initials: H
authors.lastname: Morkoç
authors.affiliation: 1Department of Materials Science and Engineering,University of Wisconsin-Madison,Madison,WI 53706,USA.
authors.forename: Paul M
authors.initials: PM
authors.lastname: Voyles