Effects of rapid thermal annealing on device characteristics of InGaAs∕GaAs quantum dot infrared photodetectors

Abstract

In this work, rapid thermal annealing was performed on InGaAs∕GaAs quantum dot infrared photodetectors (QDIPs) at different temperatures. The photoluminescence showed a blueshifted spectrum in comparison with the as-grown sample when the annealing temperature was higher than 700°C, as a result of thermal interdiffusion of the quantum dots (QDs). Correspondingly, the spectral response from the annealed QDIP exhibited a redshift. At the higher annealing temperature of 800°C, in addition to the largely redshifted photoresponse peak of 7.4μm (compared with the 6.1μm of the as-grown QDIP), a high energy peak at 5.6μm (220meV) was also observed, leading to a broad spectrum linewidth of 40%. This is due to the large interdiffusion effect which could greatly vary the composition of the QDs and thus increase the relative optical absorption intensity at higher energy. The other important detector characteristics such as dark current, peak responsivity, and detectivity were also measured. It was found that the overall device performance was not affected by low annealing temperature, however, for high annealing temperature, some degradation in device detectivity (but not responsivity) was observed. This is a consequence of increased dark current due to defect formation and increased ground state energy.

Quantum Dots as Sources and Detectors οf Mid- and Far-Infrared Radiation: Theoretical Models

“…However, in-plane polarized radiation causing transition to well bound first excited state(s) can hardly cause a strong photocurrent response. On the other hand, the mid-infrared response has been observed on many occasions in experiments performed in normal--incidence geometry [7,28,29]. This would contradict the results previously mentioned if one assumed ideally in-plane polarized radiation in these experiments.…”

A detailed investigation on the impact of post-growth annealing on the materials and device characteristics of 35-layer In0.50Ga0.50As/GaAs quantum dot infrared photodetector with quaternary In0.21Al0.21Ga0.58As capping

“…Inter-diffusion studies have been carried out on various QD structures by using the ion implantation [9] and dielectric capping [10,11] methods. Fu et al [12] ascribed a 1.3-mm shift in the spectral response from the asgrown value of 6.1 mm; however, a significant degradation of device performance was also observed. In another study, Aivaliotis et al [13] observed wide spectral tuning of InAs/In 0.15 Ga 0.85 As/ GaAs dot-in-a-well (DWELL) infrared photodetectors using postgrowth RTA, but the detectivity also decreased in the annealed QDIP.…”

Review of current progress in quantum dot infrared photodetectors

“…Reduction in vertical dot spacing increases the dark current through intradot tunneling. Experiments on rapid thermal annealing of quantum dots have shown improved PL performance but degradation in the QDIP device performance due to strain relaxation [39,80,81] has been observed. Size variation in quantum dots can be reduced by using punctuated island growth [82].…”

“…After about a decade of research, QDIPs are beginning to outperform QWIPs by demonstrating lower dark current and higher operating temperature [30][31][32]. Various groups have been working on methods to improve the structural and optical properties of quantum dots [31,[33][34][35][36][37][38][39][40] to increase carrier lifetime as well as to increase quantum dot density. Dark current levels have been significantly reduced by using AlGaAs as current blocking layers [41][42][43].…”