Maximizing output power in P-N junction betavoltaic batteries via Monte Carlo and Physics-Based Compact Model Co-Simulation*

Betavoltaic nuclear batteries show promise as compact and enduring power sources for microelectromechanical systems (MEMS). Current theoretical calculations often overlook practical diode characteristics like surface recombination (
S
), bulk recombination within the space-charge region (R-SCR), series resistance (
R_s
) and shunt resistance (
R_sh
), resulting in significant discrepancies between theoretical predictions and experimental outcomes, with differences in
J_SC
,
V_OC
, or converter efficiency up to tenfold. To address this, a Practical Diode Model, integrating these practical characteristics, is developed via Monte Carlo and Physics-Based Compact Model Co-Simulation. We quantitatively analyze the differential impacts and synergistic effects of these practical characteristics on
J_SC
,
V_OC
,
FF
, and
P_out
, highlighting the detrimental effects of
S
, R-SCR, and
R_s
, while emphasizing the beneficial role of
R_sh
. Further analysis of the degree of influence of
S
,
R_s
, and
R_sh
on output power reveals a priority ranking order of
R_s
,
S
, and
R_sh
for Si-based batteries, and
S
,
R_sh
, and
R_s
for SiC-based batteries. This approach effectively bridges the theoretical-experimental gap, evidenced by
J
−
V
curves closely matching tested batteries and minute relative errors of -0.8% to 0.6% between
P_out
values and their tested counterparts, emphasizing its accuracy in predictions. We predict output performance across material qualities, obtaining achievable powers of 16.82 and 73.90 nW/cm
²
for planar Si- and SiC-based batteries, and evaluate the quality levels of current batteries. Furthermore, our model can forecast the performance of 3D batteries by incorporating an extended electron-hole pair generation rate model into 3D structures, achieving 28 μW/cm
³
for the
⁶³
Ni-Si-based multi-layer battery, surpassing planar silicon and suitable for MEMS applications.