Electronic Properties and Their Relations to Optical Properties in Rare Earth Doped III-V Semiconductors
- PDF / 728,979 Bytes
- 12 Pages / 414.72 x 648 pts Page_size
- 103 Downloads / 197 Views
ELECTRONIC PROPERTIES AND THEIR RELATIONS TO OPTICAL PROPERTIES IN RARE EARTH DOPED III-V SEMICONDUCTORS AKIHITO TAGUCHI-, KENICHIRO TAKAHEI°, AND JYOJI NAKATAM-
"*NTT Basic Research Labs., Musashino-shi, Tokyo, JAPAN "-NTT LSI Labs., Atsugi-shi, Kanagawa, JAPAN. ABSTRACT
We discuss the energy transfer mechanism between rare-earth 4f-shells and III-V semiconductor hosts. For Yb-doped InP, we have proposed an excitation and relaxation model, which explains experimental results for the electronic and optical properties. The Yb 4fshell is excited by a recombination of an electron and a hole at an electron trap formed by Yb, which is located near the bottom of the conduction band of InP. At high temperatures, the relaxation energy of the Yb 4f-shell is back transferred as a host electron-hole pair, resulting in Yb luminescence quenching. We have found that Er-doped GaAs samples grown by metalorganic chemical vapor deposition contain as much C as Er. Rutherford back scattering and electronic property measurement results suggested that most of the Er atoms form complexes with C atoms, and these complexes are not electrically active. Such samples showed complicated Er 4f-shell luminescence spectra. To obtain a simple Er luminescence spectrum with a high peak intensity, 0 was intentionally doped with Er. Er-O complexes seemed to be formed in GaAs and these are responsible for simple and strong 4f-shell luminescence.
INTRODUCTION Rare-earth (RE) doped III-V semiconductors are attractive materials, because they have the potential to combine the advantages of optical properties of RE'+ ions and the advantages of electronic properties of semiconductor hosts. In the early 1980's, RE 4f-shell luminescence was reported for various combinations of RE's and III-V hosts synthesized by meltgrowth and ion implantation.[1] Optical properties have been widely studied, but the luminescence efficiency is still low and the intensity rapidly decreases at high temperatures. At room temperature, RE 4f-shell luminescence has been observed for a few materials such as GaAs:Er[2], GaP:Nd,[3] and GaInP:Tm.[4] To increase the efficiency and to obtain strong luminescence at room temperature, it is necessary to clarify the energy transfer mechanism between RE 4f-shells and semiconductor hosts. The electronic properties of the RE ions in III-V semiconductor hosts are important in the energy transfer mechanism. However, few studies have been carried out on these properties compared with studies on the optical properties. The electronic properties of Yb-doped InP have been most extensively studied and are well understood. 5,61 In the next section, we discuss the energy transfer mechanism between the Yb 4f-shell and InP host based on the electronic and optical properties. We show that the Yb-related electron trap level in the band gap plays an important role in the energy transfer processes. Another problem in III-V:RE materials is that the RE 4f-shell spectrum generally depends on the sample preparation method. For Er-doped GaAs, it has been reported
Data Loading...
