Regensburg 2004 – scientific programme

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HL: Halbleiterphysik

HL 26: Hauptvortrag Dadgar

HL 26.1: Invited Talk

Wednesday, March 10, 2004, 14:30–15:15, H15

Strains and stresses in GaN heteroepitaxy - sources and control — •Armin Dadgar — Institut für Experimentelle Physik, Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg

GaN epitaxy, either on sapphire, SiC or Si leads to strained layers due to several sources such as thermal strain, lattice mismatched layers as AlGaN or InGaN, strain by island growth and strain generated by doping. Using an in-situ curvature measurement technique we can observe the strain state of GaN during growth. With theoretical models we describe the evolution of stress during growth, in our case for GaN on Si. By the in-situ technique the influence of different layer schemes and of doping on stress evolution can be investigated in detail. In the case of doping we show the influence of different layer schemes on the evolution of stress. The control of strain is also important to avoid cracking of thicker layers during growth or when cooling and to obtain low-curvature layers for further processing. We show ways to control stresses and strains in GaN heteroepitaxy to achieve these goals and present latest results for GaN based devices on Si.