Options in ->Form->end()

I want to make a submit button like this:

<input type="submit" id="submit" name="submit" value="buscar" class="submit" disabled>

I have tried this, but it does not work:

<?php $opciones = ['label' => 'buscar', 'id' => 'submit', 'class' => 'submit', 'disabled' => true]; ?>
<?= $this->Form->end($opciones); ?>

oohh, I found the solution:

<?= $this->Form->submit('buscar', ['id' => 'submit', 'class' => 'submit', 'disabled' => true]); ?>