1. Introduction ................................................. 1
2. Quantum Wells ................................................ 3
3. Impurities in Bulk ........................................... 5
3.1. Effective Mass Theory ................................... 5
3.2. Donors .................................................. 6
3.3. Acceptors ............................................... 7
3.4. Isovalent Centers ....................................... 8
4. Confined Neutral Donor States ............................... 11
4.1. Theoretical Aspects .................................... 11
4.1.1. The Effective Mass Approximation ................ 12
4.1.2. The Presence of an External Field ............... 16
4.2. Experimental Aspects ................................... 18
4.2.1. Infrared Measurements ........................... 18
4.2.2. Raman Measurements .............................. 21
4.2.3. Luminescence Measurements ....................... 21
4.2.4. Selective Luminescence .......................... 28
4.2.5. Magneto-optics .................................. 31
4.2.6. Time Resolved Spectroscopy ...................... 33
5. The Negatively Charged Donor ................................ 35
5.1. Theoretical Aspects .................................... 35
5.2. Experimental Aspects ................................... 37
6. Confined Acceptor States .................................... 39
6.1. Theoretical Aspects .................................... 39
6.1.1. Effective Mass Approximation .................... 39
6.1.2. The Presence of an External Field ............... 44
6.2. Experimental Aspects ................................... 48
6.2.1. Infrared Measurements ........................... 49
6.2.2. Raman Scattering ................................ 50
6.2.3. Hole g-Values ................................... 50
6.2.4. Luminescence Measurements ....................... 52
6.2.5. Selective Photoluminescence
and Excitation Spectroscopy ..................... 53
6.2.6. Recombination Processes ......................... 53
6.2.7. Two-Hole Transitions of Bound Exciton ........... 57
6.2.8. The Dependence of the Binding Energy
on the Position in the Well ..................... 66
6.2.9. Magneto-optical Properties ...................... 71
6.2.10.Strain Effects on the Electronic Structures
of Acceptors ................................... 76
6.2.11.Dynamics ........................................ 78
7. The High Doping Regime ...................................... 87
7.1. Band Filling Effects ................................... 91
7.2. Bandgap Renormalization ................................ 96
7.3. Many Body Effects ...................................... 98
7.4. Fermi Edge Singularity ................................ 101
7.5. Charged Excitons ...................................... 101
7.5.1. Negatively Charged Excitons .................... 102
7.5.2. Positively Charged Exciton ..................... 105
7.6. Effect of an Applied Magnetic Field ................... 107
7.7. Exciton Quenching ..................................... 110
7.8. Interacting Impurities ................................ 112
8. Hydrogen Passivation ....................................... 117
9. Conclusions ................................................ 123
References .................................................... 125
Index ......................................................... 135
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