Preparation of europium‐doped GaN and AlGaN films grown by radical‐nitrogen‐assisted compound‐source MBE

Abstract

By the compound‐source molecular beam epitaxy (CS‐MBE), GaN:Eu and AlGaN films grown on both Al2O3(0001) and GaAs(100) substrates were prepared. Under RHEED observation, streak RHEED patterns from GaN were observed. This result shows that the surface of the film grown by CS‐MBE is atomically flat. From the XRD measurements, for GaN:Eu/Al2O3(0001), the film was oriented to c‐axis. On the other hands, for GaN:Eu/GaAs(100), the layer includes both the hexagonal and cubic phases. From the PL measurements, the PL spectra of both GaN:Eu/Al2O3 and GaN:Eu/GaAs(100) showed PL peaks related to Eu3+ ion. For GaN:Eu/GaAs(100), it is possible that part of Eu atom incorporates cubic‐GaN site (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Dimerization of emission centers in Eu-doped GaN red light-emitting diode: cooperative charge capturing using valence states coupling

“…However, with in incorporation, it is difficult to realize the emission of red light because the higher values of x for In x Ga 1−x N having a narrow bandgap induce a strong local internal field because of piezoelectric polarization, reducing the internal quantum efficiency [3]. A possible solution to the problem is inserting an active layer for red light emission-GaN doped with europium (GaN:Eu) [4][5][6][7][8][9]-at the p-n junction of the LED. Because Eu dopants have intra-4f transitions (typically, 5 D 0 → 7 F 2 ) at a wavelength of ~620 nm, the red LED is expected to be realized by transferring energy from the GaN host to the Eu dopants.…”

“…In previous studies, we electrically characterized the Eu emission centers in GaN:Eu LEDs according to the cutoff frequency f c [3][4][5][6][7][8][9][10][11][12][13][14][15][16]. The 'cutoff' involved in the Eu centers can be understood as follows.…”