1.3 μm-Band Laser with a High Characteristic Temperature (T0=130 K) on an InGaAs Ternary Substrate Grown by the Traveling Liquidus-Zone Method

Abstract

We have developed high-performance 1.3 µm-band laser diodes on an InGaAs ternary substrate with a low indium content (In: 0.1) grown by a novel bulk crystal growth technique (TLZ method). This laser operates at a long wavelength of 1.28 µm and at temperatures up to195 °C by using a highly strained InGaAs quantum well. The characteristic temperatures are 130 K from 25 to 95 ºC and 95 K from 95 to 155 °C. Introduction1.3 µm lasers with excellent temperature characteristics are required for low-cost telecom devices with a high bit rate. Among the many competing active layer materials, a quantum well on an InGaAs ternary substrate is advantageous for controlling the lattice constant and energy band gap and thereby provides a large conduction band offset for 1.3 µm lasers [1]. Lasers on ternary substrates with high characteristic temperatures (T 0 =140K: 20-50 ºC, 99K: 50-70 ºC@1.22 µm) [2] and that operate at high temperature (210 ºC@1.22 µm) [3] have been reported. These reported lasers with high T0 (> 100K) are HR-coated and short-wavelength (<1.26 µm) devices. Conventional InGaAs substrate (In:0.2-0.3) i s disadvantageous with respect to crystal quality and thermal conductivity compared with binary materials, such as GaAs and InP, which cause a threshold increase and e xcess heating around the active region. To overcome these problems we introduce a n InGaAs (In:0.1) substrate with a low indium composition, and we achieve 1.3 µm-band lasing by using a highly strained InGaAs multiple-quantum well. The large difference between the indium compositions of the well (>0.4) and barrier (0.1) results in a deep potential, and efficiently confines the electrons in the quantum well region. This large conduction band offset improves the temperature characteristics, as in the 1.2 µm-band highly strained InGaAs laser on GaAs [4].