technologies encodes digital information via fast and reversible transition between amorphous and crystalline phases of chalcogenide phase-change materials. [1][2][3][4][5][6][7] The phase transitions are precisely controlled by electrical pulses to realize the SET (crystallization) and the RESET (melt-quenched amorphization) operations. PCM has the characteristics of fast switching speed (<1 ns), [8] long data retention (>10 years), [9,10] and good scalability, [11,12] bridging to some extent the performance gap between the slow solid-state drive (SSD) and the fast dynamic random access memory (DRAM).The large resistance contrast (over 2-3 orders of magnitude) between amorphous and crystalline phases allows intermediate resistance states to be populated in, and thus multiple bits of data can be stored in a single memory cell, also known as multilevel cell (MLC) technology. The MLC increases the storage capacity of PCMs exponentially without changing the physical volume, and thus the cost per bit of data is remarkably reduced. Over the past years, many methods have been developed to enable MLC PCMs, including: 1) stacking multiple layers: multiple resistance levels are obtained owing to the designed heat profile inducing phase transition of chalcogenide layers sequentially; [13] 2) write programming strategy: modulating the programming pulse protocols to systematically control the volume ratio of amorphous to crystalline phases; [14,15] and 3) materials engineering: to design novel materials with multiple crystallization stages to achieve MLC. [16,17] Prototypical phase change material Ge 2 Sb 2 Te 5 (GST) has been explored for multi-bit date storage. However, the relatively low thermal stability (T c = 150 °C) and narrow voltage programming margin (i.e., the resistance is very sensitive to the change of voltage) are key issues that limit the adoption of GST in MLC applications. [18] It has been recently reported that phase change material based on pseudobinary Ga-Sb-Ge system shows fast switching speed (80 ns), good endurance (10 9 cycles), and high reliability (10 years at 220 °C). [10] Moreover, Ge-Sb, Ga-Sb, and Ge-Ga-Sb alloys were found to have a certain degree of phase separation at different temperatures, [19][20][21][22][23] which may result in variations of resistance. Based *on the above features of Phase-change memory (PCM), using the fast and reversible transition between crystal and glass to store binary data, is a promising candidate for next-generation information storage and computing technologies. Recording more than one bit of information on each memory cell, known as multilevel cell (MLC) technology, can greatly increase the data density of PCMs. In this paper, the MLC capability in a phase change material Ge-Ga-Sb (GGS) is explored. Using the "SET" operation with increasing voltage amplitudes on this PCM cell in a 250 nm pillar structure device, three resistance levels are achieved and can be stabilized within large operating voltage windows, allowing large tolerance of SET voltage variation ...