I have one custom post type named as 'portfolio', I want to customize and display archives (only cpt archives) on sidebar 'archive-portfolio.php'.

How to customize this

<?php
    wp_get_archives(
    apply_filters(
    'widget_archives_args',
    array(
        'type'   => 'monthly',
        'show_post_count' => $count,
        ),
        $instance
        )
        );
    ?>