RESONANT-CAVITY SEPARATE ABSORPTION, CHARGE AND MULTIPLICATION AVALANCHE PHOTODIODES WITH HIGH-SPEED AND HIGH GAIN-BANDWIDTH PRODUCT

Previously, it has been shown that resonant-cavity separate-absorption -and-multiplication (SAM) avalanche photodiodes (APD's) exhibit high-s peed and high gain-bandwidth products, In this letter, we describe a r esonant-cavity SAM APD with an additional charge layer that provides b etter control of the electric field profile, These devices have achiev ed bandwidths as high as 33 GHz in the low-gain regime and a record ga in-bandwidth product of 290 GHz, We also describe the correlation betw een the gain-bandwidth product and the doping level in the charge laye r, With width-dependent ionization coefficients, the current versus vo ltage (I-V) and gain-bandwidth simulations agree well with the measure d results, and indicate that even higher gain-bandwidth should be achi evable with an optimized SACM APD structure.