Conversion of p–n conduction type by spinodal decomposition in Zn-Sb-Bi phase-change alloys

Abstract

Phase-change films with multiple resistance levels are promising for increasing the storage density in phase-change memory technology. Diffusion-dominated Zn 2 Sb 3 films undergo transitions across three states, from high through intermediate to low resistance, upon annealing. The properties of the Zn 2 Sb 3 material can be further optimized by doping with Bi. Based on scanning transmission electron microscopy combined with electrical transport measurements, at a particular Bi concentration, the conduction of Zn-Sb-Bi compounds changes from p-to n-type, originating from spinodal decomposition. Simultaneously, the change in the temperature coefficient of resistivity shows a metal-toinsulator transition. Further analysis of microstructure characteristics reveals that the distribution of the Bi-Sb phase may be the origin of the driving force for the p-n conduction and metal-to-insulator transitions and therefore may provide us with another way to improve multilevel data storage. Moreover, the Bi doping promotes the thermoelectric properties of the studied alloys, leading to higher values of the power factor compared to known reported structures. The present study sheds valuable light on the spinodal decomposition process caused by Bi doping, which can also occur in a wide variety of chalcogenide-based phase-change materials. In addition, the study provides a new strategy for realizing novel p-n heterostructures for multilevel data storage and thermoelectric applications.

Recent Advances on Neuromorphic Devices Based on Chalcogenide Phase‐Change Materials

“…PCMs usually lie in the pseudobinary tie-line between GeTe and Sb 2 Te 3 in the Ge-Sb-Te (GST) [55,56] ternary phase diagram (Figure 2a). Besides the prototypical GST medium, other materials in this phase diagram such as doped Sb 2 Te [57] and pure [58] or alloyed [59,60] Sb were also frequently studied and showed excellent performance. The application of data storage exploits the fast and reversible transition between the amorphous and metastable crystalline phases of PCMs, e.g., crystallization by joule annealing or glass forming by melt-quenching (see the atomic models in Figure 2b and the memory switching operations in Figure 2c).…”

Selective Chemical Vapor Deposition Approach for Sb2Te3 Thin Film Micro-thermoelectric Generators

“…Sb2Te3 films deposited at 364 ºC demonstrates the highest power factor due to high Seebeck coefficient and moderate electrical conductivity. An average power factor over 15 µW/cm•K 2 in the temperature range from 200 K to 400 K is obtained which is competitive among some of the recent thin film works [46][47][48][49] . This demonstrates the capability of our SSP-based CVD in controlling and optimizing the thermoelectric properties.…”

Thermal analysis of novel third-generation phase-change materials with zinc as a chemical modifier

“…[4][5][6][7][8][9][10] Particularly, the recent literature survey of the last decade reveals that zinc is one of the building elements of phase change materials (PCMs) for use in phase change optical memory. [11][12][13][14][15][16][17] These features compelled various research groups to utilize Zn as a modier for preparing multicomponent (binary and ternary) ChGs. [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] Mehta et al 18 compared the effective values of thermal diffusivity and corresponding thermal conductivity of binary Se 90 Zn 10 and Te 90 Zn 10 alloys and found that both parameters are lower for Se 90 Zn 10 alloy as compared to Te 90 Zn 10 alloy.…”

“…4–10 Particularly, the recent literature survey of the last decade reveals that zinc is one of the building elements of phase change materials (PCMs) for use in phase change optical memory. 11–17 These features compelled various research groups to utilize Zn as a modifier for preparing multicomponent (binary and ternary) ChGs. 18–35…”