Photoluminescence Excitation Spectrum Of Undoped And Zn Doped Ingan Microcrystals

Two-monochomator photoluminescence (PL) and PL excitation (PLE) spectra at 77 K have been carried out on a blue band in InGaN:Zn and GaN:Zn crystals. The InGaN : Zn powder crystals were synthesized by the nitridation of a mixture of GaN:Zn microcrystals and In2S3 with NH3. PLE spectra measured in the 3.0-4.0 eV range while detecting the intensity of a blue band in the 2.7-2.8 eV range showed that a PLE band peak corresponding to the fundamental absorption edge is located at 3.47 eV and their shapes are comparable to those of GaN:Zn. Two more distinct PLE bands in the 3.4-3.1 eV range are observed while detecting the intensity in the 2.7-2.0 eV range. A PLE band located at 3.34 eV observed in both GaN:Zn and InGaN:Zn samples is assigned to Zn-related centers. A PLE band centered is located at 3.14 eV in both InGaN and InGaN:Zn while selectively excited PL bands show a red shift with an increase in nitridation temperatures. These results are discussed in terms of the localization of excitons at In-related centers like isoelectronic traps.