19 mW/μm² and 24.5 % PAE at 94 GHz for 0.30-μm Transferred InP/GaAsSb DHBT on Si-HR

InP HBT technology is a suitable candidate for the future 6G networks that require very high bandwidth. It has already demonstrated high-frequency operation with $f_{\text {max }}$ exceeding 1 THz [1]. However, this performance comes at the cost of aggressive scaling which increases thermal resistance ($R_{t h}$) due to device narrowing and leads to self-heating limiting overall performance. Transferring InP DHBT to a high-thermal-conductivity substrate has shown a drastic reduction of $R_{t h}$ by $65 \%$ on Si-HR [2] and $75 \%$ on SiC [3] thanks to their superior heat dissipation properties however its effect on output power remains unexplored. We present continuous wave (CW) large-signal load-pull measurements at 94 GHz of a transferred InP/GaAsSb DHBT transistor fabricated on a high-resistivity silicon substrate (HR-Si). The characterized device features an emitter area of $0.29 \times 4.9 \mu \mathrm{~m}^{2}$ and was biased for both maximum output power and maximum power-added-efficiency (P.A.E). A peak output power of $14.25 \mathrm{dBm}\left(18,84 \mathrm{~mW} / \mu \mathrm{m}^{2}\right)$ was achieved. This result demonstrates the impact of thermal dissipation in reducing self-heating and enabling higher output power.