Erbium-doped GaN epilayers synthesized by metal-organic chemical vapor deposition

Abstract

The authors report on the synthesis of Er-doped GaN epilayers by in situ doping by metal-organic chemical vapor deposition (MOCVD). The optical and electrical properties of the Er-doped GaN epilayers were studied by photoluminescence (PL) spectroscopy and van der Pauw–Hall method. Both above and below band gap excitation results in a sharp PL emission peak at 1.54μm. In contrary to other growth methods, MOCVD grown Er-doped GaN epilayers exhibit virtually no visible emission lines. A small thermal quenching effect, with only a 20% decrease in the integrated intensity of the 1.54μm PL emission, occurred between 10 and 300K. It was found that Er incorporation has very little effect on the electrical conductivity of the GaN epilayers and Er-doped layers retain similar electrical properties as those of undoped GaN.

Optical excitation cross section of erbium in GaN

“…Among various semiconductor host materials, the III-nitride semiconductors exhibit superior roomtemperature performance because their large energy bandgaps lead to a lower thermal quenching of Er emission [6][7][8]. Previously, we reported the synthesis of Er-doped GaN (GaN:Er) by metal-organic chemical vapor deposition (MOCVD) and the strong 1.54 μm emission using above-bandgap excitation [9,10]. The optical cross sections are fundamental parameters that determine the optical properties of devices made of GaN:Er materials.…”

Erbium-doped a-plane GaN epilayers synthesized by metal-organic chemical vapor deposition

“…The growth surface of GaN:Er epilayers grown on r-plane sapphire was determined to be aplane using x-ray diffraction (XRD) θ-2θ scan, which detected sapphire (10)(11)(12), (20)(21)(22)(23)(24), and a-plane GaN (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) reflections, as illustrated in Fig. 1.…”

“…GaN has proven to be an excellent host for Er ions [15][16][17]. C-plane Er doped GaN grown by metal organic vapor deposition (MOCVD) showed a low degree of thermal quenching (20%) between 10 and 300 K [18,19]. However, further improvements in quantum efficiency at 1.54 µm through the reduction of thermal quenching and increasing of Er incorporation in the optically active sites are still needed.…”

Spectroscopic studies of Er-centers in MOCVD grown GaN layers highly doped with Er

“…GaN samples were uniformly doped across the layers with erbium to concentrations ranging from 2 × 10 20 cm −3 up to 2 × 10 21 cm −3 . Details of the growth conditions of structures doped in situ were described in paper [12]. A control GaN sample was also grown by MOCVD method on sapphire substrate.…”