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Dr. Martin Muñoz

mmunoz@vcu.edu

(804) 828-1950

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     This figure shows that PR and CER spectra allow the determination  of the electric fields in the emitter and collector regions of the heterojuction bipolar transistor (HBT). Also the composition of the emitter can be determined.

SPS allows the determination of the base composition, providing a complementary information to CER, and PR.

Measurements by Lewis, McGlinchey, McLamb, and Muñoz. Fall/04-Spring/05.

   The nondestructive characterization/qualification of complex semiconductor multilayer structures is a crucial step in the fabrication of semiconductor materials and devices. Developmental efforts place ever increasing demands on materials and device parameters and hence evaluation procedures in order to upgrade performance and yield. Optical spectroscopies such as Photoreflectance (PR), Contact-less Electroreflectance (CER) Raman Scattering (RS) and Surface Photovoltage (SPS) are powerful tools to evaluate the performance of semiconductor heterostructures.  

PR, CER, RS and SPS spectroscopies are useful in the evaluation of the crystalline quality of the material, energy gaps[1], interband transitions and band alignment[2], energy levels of quantum dots[3] and evaluation and analysis of devices structures[4].

  At this moment, my principal interest is in the application of these techniques to large band gap materials (ZnO and GaN based), narrow band gap materials (GaSb and InAs based), nanostructures, and devices structures, such as heterojunction bipolar transistors, pseudomorphic high electron mobility transistors and quantum well lasers.

[1] Molecular Beam Epitaxial Growth and Characterization of Zincblende ZnMgSe on InP (001)    

    M. Sohel, M. Muñoz, and M. C. Tamargo. App. Phys. Lett. To be published (October,          2004).

Temperature Dependence of the Fundamental Band Gaps of GaInAsSb/GaSb and GaSb.   

     M. Muñoz, F.H. Pollak and M.B. Zakia, N.B. Patel and J.L. Herrera.    Phys. Rev. B  62, 16600 (2000).

[2] Band offset determination of Zn0.53Cd0.47Se/Zn0.29Cd0.24Mg0.47Se. 

       M. Muñoz, H. Lu, X. Zhou, M.C. Tamargo and F.H. Pollak.    Appl. Phys. Lett., 83, 1995 (2003).

[3] Contactless Electroreflectance of CdSe/ZnSe Quantum Dots Grown by Molecular Beam Epitaxy.

     M. Muñoz, S.P. Guo, X. Zhou, M.C. Tamargo, Y.S. Huang, C. Trallero and A.H. Rodríguez.   

     App. Phys. Lett. 83, 4399 (2003).

[4] Surface Photovoltage Spectroscopy and Contacless Electroreflectance Characterization of 

            GaInP/GaAs Heterojunction Bipolar Transistor Structure.   

    L. Malikova, B. Mishori, L. Mourokh, M. Muñoz, F.H. Pollak, P. Cooke, E. Armour, S. Sun and

    J. Silver.   

    Proc. of the 2000 IEEE Int. Symp. on Compound Semicon. Monterrey CA , Oct/2000. 19 (2000).

    Surface Photovoltage Spectroscopy of InGaN/GaN/AlGaN Multiple Quantum Well Light

    Emitting Diodes.   

    B. Mishori, M. Muñoz, L. Mourokh and F.H. Pollak, J.P. DeBray, S. Ting and I. Ferguson .   

    Mat. Res. Soc. Symp. Proc. Vol 680E, E4.2.1, (2001).

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