The　quasi-neutral　limit　in　a　bipolar　drift-diffusion　model　for　semiconductors　with　physical　contact-insulating　boundary　conditions,　the　general　sign-changing　doping　profile　and　general　initial　data　which　allow　the　presence　of　the　left　and　right　boundary　layers　and　the　initial　layers　is　studied　in　the　one-dimensional　case.　The　dynamic　structure　stability　of　the　solution　with　respect　to　the　scaled　Debye　length　is　proven　by　the　asymptotic　analysis　of　singular　perturbation　and　the　entropy-energy　method.　The　key　point　of　the　proof　is　to　use　sufficiently　the　fact　that　the　＇length＇　of　the　boundary　layer　is　very　small　in　a　short　time　period.　(C)　2009　Elsevier　Ltd.　All　rights　reserved.