Growth And Optical Properties Of .GaInP / AlGaInP Multi-quantum-well Epitaxial Wafers

GaInP/(AlxGa1-x)InP multi-quantum wells (MQW) is a suitable material-structure for fabrication of high-brightness emitting diodes (HB-LED). HB-LEDs have become new attractive light sources with superiority in small volume, high energy efficiency and long life time and have extensive prospect in communication, traffic and information displaying. In particularly, LEDs have become attractive for their prospect of becoming the new illuminating source.In order to improve the design of MQW structure and the quality of material, GaInP/(AlxGa1-x)InP MQW have been manufactured and analyzed by photoluminescence and Raman. Great achievements have been obtained.(1) The theory of photoluminescence of GalnP/AlGalnP MQW was analyzed. A strong peak at and a weak peak at on the photoluminescence spectrum (PLS) were observed. The calculation results are basically in agreement with the actual results. Some useful data for material growth and structure design can be obtained by analyzing PLS, which will benefit the quality of LEDs greatly.(2) Several samples of different structure parameters are grown by low-pressure metal-organic chemical vapor deposition (LP-MOCVD). It is found that PL peak intensity, full width at half maximum (FWHM) and light output intensity are greatly dependent on number of wells. Ratio of well/barrier width nearly has no effect on PL peak intensity and FWHM, but has little relation to light output intensity. And emission wavelength depends on Ratio of well/barrier width more than number of wells. Some useful data has been found through experiments.(3) GalnP/AlGalnP MQW samples of different numbers of wells are grown and their Raman spectra are measured. Many idiosyncratic phononmodes are observed in Raman spectra. According to the Raman selection rule and the PL measurement, it is reasonable to evaluate the quality of GalnP/AlGalnP MQW by analyzing the relative intensity ratio of A1P-LO/TO.(4) A new modified random element isodisplacement (MREI) model is set up to calculate the dependence between the long-wavelength optical phonon frequencies and the composition of III-V-type AB1-xCx mixed crystals. The second neighbor force constants are still assumed to be a linear variation with the composition, but the two first neighbor force constants can be evaluated to be a negative exponent variation with the composition, using the overlapped repulsive potential of the ion crystal combination. At last the calculated result of AsAl1-xGax and SbAl1-xGax is found to be in good accordance to the experimental data.( 5 ) On the basis of III-V-type AB1-xCxmixed crystals, MREI model is generalized to the III-V (AxB1-x) 1-yCyD-type quaternary alloys, describing the behavior of the optical phonons. The calculated result of two quaternary mixed crystals, (AlxGa1-x) 1-yInyP and (AlxGa1-x)1-yInyAs, is in good agreement to the experimental data. Their composition will be estimated conveniently by Raman spectra and the model.