AVS 52nd International Symposium
    Science of Semiconductor White Light Topical Conference Monday Sessions
       Session WL-MoA

Paper WL-MoA3
Indium Incorporation Studies for Blue and Green Emitting Multi-Quantum Wells and Light Emitting Diodes

Monday, October 31, 2005, 2:40 pm, Room 310

Session: Science of Semiconductor White Lighting
Presenter: D.D. Koleske, Sandia National Laboratories
Authors: D.D. Koleske, Sandia National Laboratories
S.R. Lee, Sandia National Laboratories
A.J. Fischer, Sandia National Laboratories
M.H. Crawford, Sandia National Laboratories
M.E. Coltrin, Sandia National Laboratories
M.J. Russell, Sandia National Laboratories
K.C. Cross, Sandia National Laboratories
Correspondent: Click to Email
While the promise for tuning the bandgap from 0.7 to 6.2 eV in the group III nitride materials system exists, achieving wavelengths greater than 530 nm is difficult due to several factors. These factors include the disparate growth conditions that must be used for In incorporation, especially temperature, and the lattice mismatch between GaN and InGaN alloys, which may induce compositional instability and decrease structural ordering. The issue of In incorporation becomes particularly important for improving light emission for green LEDs, where the internal quantum efficiency is significantly less than for blue LEDs. Currently, we are investigating the growth of InGaN multi-quantum wells (MQWs) with the aim of understanding how the growth conditions influence In incorporation. The MQW structure is analyzed using x-ray diffraction and dynamical diffraction theory is used to determine the In content and quantum well thickness. Photoluminescence and fabrication of simple LEDs were used to characterize the photo- and electro-luminescence properties of the films. We explored two different growth regimes for improving In incorporation into the QWs. The first growth regime involved growing the MQWs with very high growth rates to capture and bury the In before it desorbs. In this fast growth regime, we were able to incorporate up to 18 % In into the MQWs at 770 °C, leading to 470 nm LED emission. A subsequent reduction of the growth temperature to 725 °C produced green LEDs emitting at 510 nm. The second growth regime involves slower growth rates and lower growth temperatures which allows for increased In residence time on the surface, potentially leading to higher In content in the MQWs. Advantages and disadvantages of both growth regimes will be discussed with a focus on identifying the growth regime that enables the highest luminescence efficiency in green MQWs and LEDs