The effect of the surface band bending on the optical emission from AlGaN/GaN multi quantum well structures (MQWs) has been evidenced by comparison of two different type of MBE samples, surface and buried MQWs, both experimentally by photoluminescence (PL) spectroscopy and theoretically by Poisson-Schrodinger self consistent calculations. The same structures are used both grown on a GaN buffer, with the only difference that a 100 nm thick GaN cap layer has been grown on the MQW in case of the buried sample. The major difference between the PL spectra of both samples is a blue shift in the MQW surface sample, which let us identify as a main feature an enhanced emission from the first QW, just below the surface. The surface electric field induced by the pinning of the Fermi level is opposite to the polarization field in the GaN well, such that the overall field is reduced, in particular in the first well, with an increased spatial overlap of the electron and hole wave functions.
Optical emission from surface and buried AlGaN/GaN MQWs grown by MBE on 6H-SiC
Lomascolo M;
2000
Abstract
The effect of the surface band bending on the optical emission from AlGaN/GaN multi quantum well structures (MQWs) has been evidenced by comparison of two different type of MBE samples, surface and buried MQWs, both experimentally by photoluminescence (PL) spectroscopy and theoretically by Poisson-Schrodinger self consistent calculations. The same structures are used both grown on a GaN buffer, with the only difference that a 100 nm thick GaN cap layer has been grown on the MQW in case of the buried sample. The major difference between the PL spectra of both samples is a blue shift in the MQW surface sample, which let us identify as a main feature an enhanced emission from the first QW, just below the surface. The surface electric field induced by the pinning of the Fermi level is opposite to the polarization field in the GaN well, such that the overall field is reduced, in particular in the first well, with an increased spatial overlap of the electron and hole wave functions.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
