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During the last 25 years (after the growth of the first pseudomorphic GeSi strained layers on Si by Erich Kasper in Germany) we have seen a steady accu mulation of new materials and devices with enhanced performance made pos sible by strain. 1989-1999 have been very good years for the strained-Iayer devices. Several breakthroughs were made in the growth and doping technology of strained layers. New devices were fabricated as a results of these break throughs. Before the advent of strain layer epitaxy short wavelength (violet to green) and mid-IR (2 to 5 f. Lm) regions of the spectrum were not accessi ble to the photonic devices. Short wavelength Light Emitting Diodes (LEDs) and Laser Diodes (LDs) have now been developed using III-Nitride and II-VI strained layers. Auger recombination increases rapidly as the bandgap narrows and temperature increases. Therefore it was difficult to develop mid-IR (2 to 5 f. Lm range) lasers. The effect of strain in modifying the band-structure and suppressing the Auger recombination has been most spectacular. It is due to the strain mediated band-structure engineering that mid-IR lasers with good per formance have been fabricated in several laboratories around the world. Many devices based on strained layers have reached the market place. This book de scribes recent work on the growth, characterization and properties o(compound semiconductors strained layers and devices fabricated using them.
Sommario
1 Introduction.- 1.1 Evolution of strained layers.- 1.2 Conventional III-V-based heterostructures.- 1.3 III-Nitrides.- 1.4 Wide bandgap II-VI semiconductors.- 1.5 Material parameters.- 1.6 Scope and organization of this book.- 2 Characterization and growth.- 2.1 Methods of characterization.- 2.2 Epitaxial growth methods.- 2.3 Growth of conventional III-V semiconductors.- 2.4 Growth of II-VI semiconductors.- 2.5 Growth of Ill-nitride epilayers.- 3 Strain and critical thickness.- 3.1 Strain and energies of epilayers.- 3.2 Processes involved in dislocation generation.- 3.3 Critical thickness.- 4 Strain relaxation and defects.- 4.1 Strain in GeSi layers.- 4.2 Strain in III-V semiconductor layers.- 4.3 Strain in II-VI layers.- 4.4 Strain and defects in Ill-Nitride layers.- 5 Band structure and optical properties.- 5.1 Band structure.- 5.2 Band offsets.- 5.3 Optical properties of III-V semiconductors.- 5.4 Optical properties of II-VI semiconductors.- 5.5 Optical properties of Ill-Nitrides.- 6 Electrical and magnetic properties.- 6.1 Electrical properties of II-VI semiconductors.- 6.2 Electrical properties of n-type GaN.- 6.3 Electrical properties of p-type Ill-Nitrides.- 6.4 Electrical properties A1N, InN and alloys.- 6.5 Schottky barriers and ohmic contacts.- 6.6 Effect of applied electric field.- 6.7 Piezoelectric effect.- 6.8 Effect of magnetic field on semiconductors.- 7 Strained layer optoelectronic devices.- 7.1 Conventional-Ill-V semiconductor lasers.- 7.2 ZnSe-based light emitters and other devices.- 7.3 Other II-VI semiconductor applications.- 7.4 Ill-Nitride Light Emitting Diodes.- 7.5 GaN based Lasers.- 8 Transistors.- 8.1 InGaAs transistors.- 8.2 II-VI semiconductor transistors.- 8.3 Ill-Nitride based transistors.- 8.4 Device Processing.- 9 Summary and conclusions.- 9.1 Growth, defects and strain.- 9.2 Band structure and electronic properties.- 9.3 Applications and future work.- Appendix A.
