ABSTRACT
INFM and Dipartimento di Fisica, University di Roma, "La Sapienza," Italy
6.1 INTRODUCTION 162 6.2 EXPERIMENTAL: HYDROGENATION AND
CHARACTERIZATION TECHNIQUES 164 6.3 EFFECTS OF NITROGEN AND HYDROGEN ON THE
ELECTRONIC PROPERTIES OF InxGai_„Asi_yNy 165 6.3.1 The N Isoelectronic Impurity in GaAsi.),Ny 165 6.3.2 Effects of Hydrogen on the Electronic
Properties of In„Gai.xAs 166 6.3.2.1 Restoration of the host band-gap by
hydrogenation: dilute, amalgamation, and alloy limits 166
6.3.2.2 Activation energies for the removal of hydrogen: evidences for multiple N-containing complexes 167
6.3.2.3 Restoration of the host conduction band structure by hydrogenation: electron effective mass and exciton Bohr radius 174
6.3.2.4 Restoration of the temperature coefficient 180 6.3.2.5 Effect of hydrogen on the lattice structure
of GaAsi 181 6.4 EFFECT OF HYDROGEN ON THE ELECTRONIC
PROPERTIES OF GaPi_yNy 184 6.5 ROLE OF THE N-11; COMPLEX 186 6.6 CONCLUSIONS 189
Acknowledgments 190 References 190
6.1 INTRODUCTION
Hydrogen is the smallest and one of the most chemically active atoms. It dramatically affects the electronic properties of crystalline semiconductors, as first discovered in ZnO [1]. Hydrogen easily diffuses in semiconductors [2] and neutralizes dangling bonds, thus cleaning up the band-gap from defect energy levels. Because hydrogen is present in the plasmas, etchants, precursors, and transport gases of most growth processes and device massproduction steps, a great interest has been focused on the effects of hydrogen in the semiconductors that are used to produce modern devices [3]. Hydrogen-related centers were recognized in ultrapure germanium [4], and neutralization of boron acceptors has been discovered in silicon [5, 6], which suggests the existence of H-related donor levels in the band-gap [7, 8]. It was later shown that hydrogen can passivate donors as well, due to its amphoteric impurity behavior in both elemental and compound semiconductors [9, 10]. This impurity passivation was explained in terms of the formation of complexes made of one H atom and one impurity [11, 12], and hydrogen-impurity bonds were detected, indeed, by infrared absorption spectroscopy [13-16] .
