NEUTRALIZATION OF DEFECTS AND DOPANTS IN III-V SEMICONDUCTORS

This chapter describes the neutralization of defects and dopants in III–V semiconductors. The chapter presents a review on the effects of hydrogen (H) in III–V semiconductors. In GaAs, the neutralization of silicon (Si) donors reduces the concentration of free electrons but increases the mobility of the remaining electrons. The H-donor complex is stable to 250°C. Evidence that H bonds directly to donor impurities is provided by the observation that the dissociation energy scales with the H-donor bond strength; the dissociation energy for the Si–H complex is 2.1 eV. In photoluminescence, the hydrogen neutralization of dopants is manifested by the disappearance of bound excitons. In GaAs, acceptor-H complexes are less stable than donor-H complexes. Some hydrogenation techniques may induce surface damage that increases the H concentration at the surface. Some of the compounds tend to decompose during hydrogenation—for example, the surface of indium phosphide (InP) decomposes with the formation of phosphine (PH3). This problem has been controlled by encapsulating the substrate with a hydrogen-permeable layer. © 1991, Elsevier Inc. All rights reserved.