Problem with ADM8828 regulation

I am trying to use ADM8828 to provide -5V rail.

-5V is output under open circuit, no load conditions.

But with any load connected the output voltage slumps, e.g. -0.5V across 270 Ohm.

ADM8828 datasheet RevA p 2 recommends electrolytic charge pump capacitors having ESR <0.2 Ohm.

However, I am using 1uF tantalum types, ESR 7.5 Ohm, only because they were to hand and available from my stock.

Could this be the cause of the poor regulation ?

What polarized capacitor types have ESR < 0.2 Ohm and can be recommended ?

As long as ESR is very low, do the capacitors need to be polarized, what are the alternatives ?

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