Phase Change Dynamics and Two-Dimensional 4-Bit Memory in Ge2Sb2Te5 via Telecom-Band Encoding
We propose and demonstrate a two-dimensional 4-bit fully optical nonvolatile memory using Ge2Sb2Te5 (GST) phase change materials, with encoding via a 1550 nm laser. Using the telecom-band laser, we are able to reach deeper into the material due to the low-loss nature of GST at this wavelength range, hence, increasing the number of optical write/read levels compared to previous demonstrations, while simultaneously staying within acceptable read/write energies (maximum 60 nJ/bit for write, depending on the number of pulses). For our experimental results, 50 ns long pulses with a 25 ns fall time, a peak power of 200 mW, and a 125 kHz repetition rate were used. We verify our design and experimental results via rigorous numerical simulations based on finite element and nucleation theory, and we successfully write and read a string of characters using direct hexadecimal encoding.
National Science Foundation, 1709200
Sevison, Gary A. A.; Farzinazar, Shiva; Burrow, Joshua A.; Perez, Christopher; Kwon, Heungdong; Lee, Jaeho; Asheghi, Mehdi; Goodson, Kenneth E.; Sarangan, Andrew M.; Hendrickson, Joshua R.; and Agha, Imad, "Phase Change Dynamics and Two-Dimensional 4-Bit Memory in Ge2Sb2Te5 via Telecom-Band Encoding" (2020). Electro-Optics and Photonics Faculty Publications. 134.