biaxial strain modified acceptor activation energy of wurtzite gan analyzed by k p method n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Biaxial Strain-modified Acceptor Activation Energy of Wurtzite GaN Analyzed by k?p Method PowerPoint Presentation
Download Presentation
Biaxial Strain-modified Acceptor Activation Energy of Wurtzite GaN Analyzed by k?p Method

Loading in 2 Seconds...

play fullscreen
1 / 16

Biaxial Strain-modified Acceptor Activation Energy of Wurtzite GaN Analyzed by k?p Method - PowerPoint PPT Presentation


  • 106 Views
  • Uploaded on

Biaxial Strain-modified Acceptor Activation Energy of Wurtzite GaN Analyzed by k∙p Method. Presented by: Ning Su John Simon Lili Ji Instructor: Dr. Debdeep Jena. 12/13/2004. EE698D Advanced semiconductor physics. Outline.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Biaxial Strain-modified Acceptor Activation Energy of Wurtzite GaN Analyzed by k?p Method' - albert


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
biaxial strain modified acceptor activation energy of wurtzite gan analyzed by k p method

Biaxial Strain-modified Acceptor Activation Energy of Wurtzite GaN Analyzed by k∙p Method

Presented by: Ning Su

John Simon

Lili Ji

Instructor: Dr. Debdeep Jena

12/13/2004

EE698D Advanced semiconductor physics

outline
Outline
  • Introduction
    • Background
    • Motivation
  • Band structure calculation
    • Conduction and valence band Hamiltonian
    • Band structure modification by biaxial strain
  • Acceptor activation energy and conductivity
    • Density of States (DOS) calculation
    • Effective mass calculation
  • Conclusion

EE698D: Advanced Semiconductor Physics

introduction
Introduction
  • Role of strain on electronic and optical properties of semiconductors has been carefully studied for several decades

device applications: HBTs

Lasers

  • To better understand the effect of strain on semiconductor properties, fundamentalstudies of band structure is of great importance

e.g. 1)tight-binding method

2) K∙P method--- used in this work

EE698D: Advanced Semiconductor Physics

introduction cont d
Introduction-cont’d
  • Biaxial strain in Wurtzite Gallium Nitride (GaN)
    • Large biaxial strain in bulk wurtzite GaN large lattice

mismatch between GaN & substrate, post-cooling

    • Less well understood compared to zinc-blend GaN
  • Acceptor activation energy in GaN
    • Large Ea of Mg-doped GaN (120~260meV) limits room temperature p-GaN conductivity
    • Strained modified Ea, a potential way to improve electrical property

Motivation of this work !!

EE698D: Advanced Semiconductor Physics

simulation model
Simulation Model

k∙P method

Hamiltonian derivation

Band Structure under strain

m* tensor

DOS

Hole distribution

mobility

Fermi-Direc

conductance

life time

Critical thickness

EE698D: Advanced Semiconductor Physics

band structure under strain
Band Structure under Strain
  • Conduction and valence bands Hamiltonian
    • Conduction band

( parabolic band model)

    • Valence band (ref. a)

where and

  • Band structure can be obtained by finding eigenvalues of the Hamiltonians defined above

ref. a: S. L. Chuang and C. S. Chang, Phys. Rev. B, 54, 2491 (1996)

EE698D: Advanced Semiconductor Physics

slide7

Band structure-cont’d

  • Energy values for band edge

as a function of strain ( -2%~2%)

  • At the tensile strain of 0.107%,

the LH band rises above the HH

band edge

  • Band gap for compressive strain

for tensile

EE698D: Advanced Semiconductor Physics

slide8

Band structure-cont’d

  • Valence band dispersions

1% compressive

unstrained

  • kx and kz are transverse and longitudinal axes along [0001] direction

1% tensile

EE698D: Advanced Semiconductor Physics

acceptor activation energy
Acceptor Activation Energy
  • Assumption:

Acceptor energy level is

fixed with respect to

vacuum level

  • Typical value of EA =160 meV is chosen for Mg-doped

GaN

  • EA decreases faster with

tensile strain

EE698D: Advanced Semiconductor Physics

effective mass
Effective Mass

effective mass as a function of strain derived from band structure

EE698D: Advanced Semiconductor Physics

dos and hole distribution
DOS and Hole Distribution

DOS

Hole distribution

Fermi-Dirac

function

EE698D: Advanced Semiconductor Physics

hole concentration
Hole Concentration

NA=1018cm-3

Hole concentration as a function a strain

EE698D: Advanced Semiconductor Physics

mobility and conductivity
Mobility and Conductivity

Mobility and conductivity along transverse and longitudinal directions under strain (Assume life time =0.1ns )

EE698D: Advanced Semiconductor Physics

conductance
Conductance

Critical thickness is used for the layer thickness

EE698D: Advanced Semiconductor Physics

conclusion
Conclusion
  • Strain modified Band structure was calculated using k∙p method
  • Acceptor activation energy was found to decrease with strain
  • Hole concentration increases rapidly with tensile strain
  • µ & σ was enhanced in the [0001] direction

EE698D: Advanced Semiconductor Physics

acknowledgement
Acknowledgement

We acknowledge Prof. Debdeep Jena for his directions and helpful discussions.

EE698D: Advanced Semiconductor Physics