Extremely Large Er Excitation Cross Section in Er,O-Codoped GaAs Light Emitting Diodes Grown by Organometallic Vapor Pha
- PDF / 862,271 Bytes
- 6 Pages / 595 x 842 pts (A4) Page_size
- 32 Downloads / 166 Views
M4.8.1
Extremely Large Er Excitation Cross Section in Er,O-Codoped GaAs Light Emitting Diodes Grown by Organometallic Vapor Phase Epitaxy Yasufumi FUJIWARA, Atsushi KOIZUMI, Kentaro INOUE, Akira URAKAMI, Taketoshi YOSHIKANE, and Yoshikazu TAKEDA Department of Materials Science and Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan ABSTRACT Room-temperature Er-related electroluminescence (EL) properties have been investigated in Er,O-codoped GaAs (GaAs:Er,O) light emitting diodes (LEDs) grown by organometallic vapor phase epitaxy (OMVPE). Under forward bias, characteristic emission due to a luminescence center consisting of Er coordinated by O and As was clearly observed at room temperature, while the Er-related EL was undetectable under reverse bias. At lower current densities, the EL intensity increased linearly with the current density. Subsequently, the intensity exhibited a tendency to saturate at higher current densities. By analyzing the behavior with a fitting according to rate equations, the excitation cross section of Er ions due to current injection was determined to be approximately 10-15 cm2, which is by five orders in magnitude larger than that for optical excitation in Er-doped fiber amplifiers (10-20~10-21 cm2). INTRODUCTION Er atoms doped in III-V semiconductors and silicon exhibit a sharp and temperature-stable luminescence at around 1.5 µm due to intra-4f shell transitions from the first excited state (4I13/2) to the ground state (4I15/2) of Er3+. The wavelength of 1.5 µm lies in the minimum loss region of silica fibers. These properties are attractive for fabricating optical devices such as semiconductor lasers and optical amplifiers. We have intensively investigated OMVPE growth and luminescence properties of Er-doped III-V semiconductors [1]. In GaAs:Er,O, the Er-related photoluminescence (PL) spectrum was dominated by seven emission lines under host-excited conditions at a low temperature [2]. The Er center has been identified as an Er atom located at the Ga sublattice with two adjacent O atoms (hereafter referred as Er-2O) together with two As atoms [3,4]. The dependence of the Er-related PL spectra on growth temperature revealed the existence of a threshold growth temperature (543-585ºC) [5]. Above the threshold growth temperature, the formation of the Er-2O center was suppressed greatly. In this paper, we report on the fabrication of GaAs:Er,O LEDs by OMVPE and their EL properties at room temperature. Extremely large excitation cross section of Er ions has been successfully obtained in the LEDs. EXPERIMENTAL DETAILS A low-pressure growth system with a vertical quartz reactor was utilized in this work [6]. TEGa and TBAs were used as source materials for GaAs growth. Er was doped with trisisopropylcyclopentadienylerbium (Er(i-PrCp)3). The Er source was maintained at a constant temperature of 90˚C and introduced into the reactor by a H2 flow through a source
M4.8.2
cylinder. 18O2 of 38.4 ppm in Ar gas was used as an O2 source. The O2
Data Loading...
