Electron beam pumping in nitride vertical cavities with GaN/Al0.25Ga0.75N Bragg reflectors

Electron beam pumped surface emitting lasers are of great interest for a va riety of applications, such as Laser Cathode Ray Tubes (LCRT) in projection display technology or high power UV light sources for photolithography. Two distributed Bragg reflector (DBR) samples were grown by plasma assisted molecular beam epitaxy (PAMBE). The active regions of the samples are a Ga N:Si bulk layer and a multihetero (MH) structure, respectively. Also, a separately grown single DBR stack was studied to find optical trans mission and reflection properties which were compared to transfer matrix si mulations. Scanning electron beam pumping at 80 K with an excitation energy of 40 keV at varying beam currents revealed luminescence emission maxima l ocated at about 3.45 eV for the sample with the MH structure active region. Optical modes appeared for excitation powers greater than 0.85 MW/cm(2). F urther increasing the excitation power density the number of modes increase d and a broadening and redshift of the luminescence spectrum could be obser ved. Based on our experimental results, we discuss the dependence of optical par ameters of the nitride vertical cavity and sample surface reactions on prim ary electron beam power.