ABSTRACT
Abstract. We report an electrically pumped MOVPE-grown GalnNAs laser diodes emitting at 1.36um with low threshold current. The key process parameter to achieve the high quality GalnNAs QW structure was discussed
1. Introduction The GalnNAs quantum well (QW) on a GaAs substrate is a very promising alternative to conventional InP-based technology for realizing high performance and cost effective laser diode (LD) in the 1300nm range. Since the successful demonstration of 1300nm GalnNAs lasers [1] and vertical cavity surface emitting lasers (VCSELs) [2], efforts to push the devices to longer wavelength have been under taken. Recently, several research groups have demonstrated long wavelength GalnNAs lasers in the 1.3 pm range using molecular beam epitaxy (MBE) [3-4]. However, the lasing wavelength of GalnNAs lasers grown by MOVPE, which is regarded as a more promising technology to achieve high quality AlAs/GaAs distributed Bragg reflector (DBR) with cost effectiveness, has been remained in the relatively short wavelength region [5]. In this paper, we propose a new QW structure with multiple barriers (InGaAs/GaNAs) for achieving high-quality long wavelength emission over 1.3pm. The studies reported here indicate that the PL efficiencies of the GalnNAs QW was significantly improved by adoption of the multiple barriers, compared to that of the QW with conventional GaAs barrier. The feasibility of the proposed QW structure was evaluated by an oxide stripe laser diodes (LD). The details of lasing characteristics has been summarized
2. Experimentals Epitaxial growth was carried out in horizontal type reactor under low pressure (lOOmbar) on epi-ready (001) GaAs substrate. Triethylgallium (TEG), trimethyl indium (TMI), Tertiarybutylarsine (TBA) and 1,1-dimethyl hydrazine (DMHy) were used as precursor to grow GalnNAs quantum well. QW growth temperature was 470°C. For the growth of stripe LD structure, Arsine (ASH3) was also used to grow high temperature (650°C) GaAs and AlGaAs layers. The dopant sources were SiR* and CBr4. An 8nm GalnNAs single quantum well was located at the center of 200 nm-thick undoped GaAs waveguide. The n-and p-type cladding layers consist of 1.5 pm Alo.5Gao.5As doped with Si and C to about 1 x 1018 cm'3. All GalnNAs QW samples were annealed using a rapid thermal
annealer between 550°C and 700 °C for 0.5 to 2min in nitrogen ambient. After structure growth, 50 pm wide oxide stripe lasers were fabricated. A Ti/Pt/Au and a AuGe/Ni/Au metallizations were used for p-and n-ohmic contacts, respectively. The wafer was cleaved to chips of 800 pm in length. The thickness and the composition of the QW were derived from high resolution X-ray diffraction (HR-XRD) on calibration samples, which were crosschecked with high-resolution transmission electron microscope (TEM) and secondary ion mass spectrometry (SIMS). Room temperature Photoluminescence (PL) with a He-Ne laser as excitation source was carried out to evaluate the optical properties of QW.
