Figures

Figure 1

Time-integrated photoluminescence spectra of a series of GaN/AlGaN quantum wells. The dashed line indicates the position of the GaN bandgap.

Figure 2

Double-logarithmic plot of the luminescence decay for a 2 nm, a 5 nm, and a 10 nm GaN/AlGaN quantum well. The thickest layer shows a decay on a microsecond timescale.

Figure 3

Schematic picture of the energies and wavefunctions of electrons and holes in a strained quantum well with a piezoelectric field.

Figure 4

Comparison of the measured energy positions (dots) and decay times (squares) of the low-energy lines in GaN/AlGaN SQW's with a calculation based on piezoelectric fields. The triangles give the values for the respective higher-energy emission lines.

Figure 5

Comparison of the measured energy positions (dots) and decay times (squares) of the low-energy lines in GaInN/GaN SQW's with a calculation based on piezoelectric fields.

Figure 6a

Layer sequence of the asymmetric GaN/GaInN/AlGaN test structures.

Figure 6b

Layer sequence of the asymmetric GaN/GaInN/AlGaN test structures.

Figure 7

Comparison of the luminescence decay after pulsed excitation for the two test samples with an AlGaN barrier above or below the GaInN quantum well.

Figure 8

Comparison of the measured decay times for the test samples with those from symmetric GaInN/GaN quantum wells with the sample In mole fraction.

Figure 9

Schematic view of the conduction band in the sample with an AlGaN barrier below the GaInN quantum well.

Figure 10

Schematic view of the conduction band in the sample with an AlGaN barrier on top of the GaInN quantum well.

Figure 11

Time-resolved photoluminescence spectra of the GaN/GaInN/AlGaN quantum well showing the effect of screening of the piezoelectric field by photogenerated carriers.

Figure 12

Photoluminescence and stimulated emission spectra of GaInN/GaN quantum wells with 3 nm and 6 nm well thickness.

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