Effect of Si and Er Co-doping on Green Electroluminescence from GaN:Er ELDs
- PDF / 204,855 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 16 Downloads / 189 Views
1068-C05-03
Effect of Si and Er Co-doping on Green Electroluminescence from GaN:Er ELDs Rui Wang, and Andrew J Steckl Department of Electrical & Computer Engineering, University of Cincinnati, Cincinnati, OH, 45221-0030 ABSTRACT (Er, Si) co-doped GaN thin films were grown on Si substrates by molecular beam epitaxy (MBE) technique. Electroluminescent devices (ELDs) were fabricated and the effect of Si codoping on the performance of GaN devices was studied. Previous results with GaN:Er ELDs reported that electroluminescence (EL) was much stronger in reverse bias than in forward bias condition, indicating that the dominant factor in EL intensity was the electric field. The results reported here show the first time GaN:Er ELDs where forward bias EL is very much larger, indicating that the dominant factor is forward bias current. The electrical properties of (Si, Er) co-doped GaN thin films are believed to be responsible for the current control mechanism. INTRODUCTION Rare earths are of interest in optoelectronics and photonics because of their sharp emission lines. For example, Er has emission lines at both visible (538nm and 559nm) and infrared (1.54um) wavelengths, which are very useful for display devices and optical communications. Although the emission spectrum is independent of host materials, the intensity and efficiency strongly depend on the host. It was found by Favennec[1] that thermal quenching of the RE emission is inversely dependent on the energy bandgap of host materials. Therefore, III-nitride semiconductors are excellent host materials because of their direct wide bandgap. Moreover, robust thermal and mechanical properties of nitride semiconductors enable device applications under high temperature environment. Sapphire and SiC are typically used as substrates for GaN thin film growth because their lattice constants are close to III-nitrides. However, GaN growth on Si substrates is very attractive for integration with Si microelectronics.[2] The first report[3] of electroluminescence (EL) from GaN:Er was for diodes actually grown on Si substrates and utilized a Schottky barrier structure. Subsequently, visible and IR EL emission from GaN:Er Schottky diodes was reported[4] on Si and sapphire substrates. Zavada et al[5] reported EL emission from GaN:Er P-I-N LED on sapphire. In general, in all of these devices the EL emission was much stronger in reverse bias than in forward bias. Here we report on Er-doped GaN ELD on Si wafer with Si co-doping. The effect of Si and Er co-doping on electrical properties and Er green electroluminescence in the GaN layer was studied. EXPERIMENT GaN thin films were grown with Er and Si in situ doping on p-type Si(111) substrates in a solid source Riber 32 MBE system. A 20nm low temperature AlN buffer layer was first grown at 500ºC, followed by 1hr growth of (Si, Er) co-doped GaN layer. A very thin GaN capping layer
was grown last. The substrate temperature was kept at 600ºC. The Ga effusion cell temperature was kept at 875ºC, while the Si and Er cell temperatures were kep
Data Loading...
