Principal Investigator Gang Chen
Overheating presents a major challenge in modern electronics industry due to the increasingly higher power density. High temperatures not only limit de- vice performance, but also greatly reduce reliability and lifetime. To effectively dissipate heat from an elec- tronic chip, materials with high thermal conductivity (k) are crucial. Common electronic materials such as copper and silicon exhibit a room temperature (RT) k of 401 Wm-1K-1 and 148 Wm-1K-1, respectively. In compar- ison, diamond holds the current k record of about 2000 Wm-1K-1 at RT. However, natural diamond is scarce, and synthetic diamond still suffers from slow growth, low quality, and high cost. In addition, significant thermal stresses can arise from the large mismatch in the co- efficient of thermal expansion between diamond and common semiconductors.
Recently, first-principles calculations predicted a very high RT k of about 1400 Wm-1K-1 for cubic boron arsenide (BAs), rendering it a close competitor for diamond. The materials collaborators from the University of Houston and UCLA have grown samples of different sizes and qualities. We carried out thermal transport measurement of these sub-millimeter to millimeter-sized samples using time-domain thermoreflectance (TDTR), among other methods. In some samples, we have reached thermal conductivity as high as 1200 Wm-1K-1.
We have also carried out the first-principles calculation of electron and hole mobility in boron- based III-V materials. We predict that BAs has both high electron (1400 cm2V-1s-1 at RT) and hole (2110 cm2V- 1s-1 at RT) mobility (Figure 2). These characteristics, together with the high thermal conductivity, make BAs attractive for microelectronics applications both as device materials and as heat sink materials.