Molecular Beam Epitaxy

7MBE of III‐Nitride Semiconductors for Electronic Devices

Rolf J. Aidam O. Ambacher E. Diwo B.‐J. Godejohann L. Kirste T. Lim R. Quay and P. Waltereit

Fraunhofer Institute for Applied Solid State Physics, 79108 Freiburg im Breisgau, Germany

7.1 Introduction

GaN and its alloys with InN and AlN enable various applications in electronics and optoelectronics due to the wide range of band gaps (Figure 7.1). Especially it is suitable for high‐frequency power amplification [1] because of its large breakdown electric field of 3.3 MV cm⁻¹ and high saturation velocity of 2.5 × 10⁷ cm s⁻¹. Nowadays, metal organic vapor‐phase epitaxy (MOVPE) is the most common method in GaN electronic industries, as it allows high growth rates and throughput. However, molecular beam epitaxy (MBE) is an attractive method for epitaxial growth of III‐nitride semiconductor‐based electronic devices. In comparison to MOVPE, sharper interfaces and lower impurity levels can be obtained, which supports the fabrication of heterostructures with excellent electronic properties. In addition, the lower growth temperature enables epitaxy of In‐containing layers like GaInN [2,3], AlInN [4,5], and AlGaInN [6,7], which are very interesting for high‐power devices at high frequencies.

Figure 7.1 In‐plane lattice parameters and band gaps for GaN(0001) and its related alloys. The in‐plane lattice parameters and bandgaps of common substrates ...