EFFECTIVE NITROGEN DOPING INTO EPITAXIALLY GROWN P-TYPE ZnSe

1. p型ZnSe外延生长的有效氮种依次为(1)原子氮，(2)激发和电离的氮分子，(3)激发的中性氮分子。进一步加速电离氮会导致晶体缺陷。随着氮掺杂量的增加，光致发光光谱中的优势发射峰发生了变化：(1)激子发射结合中性氮受体，(2)从导带过渡到氮受体水平，(3)浅给体向氮受体对发射，(4)深给体向氮受体对发射。氮掺杂ZnSe的补偿供体是：(1)源材料中残留的供体杂质（通常是Se中的Cl），(2)生长气氛中的氢和(3)特别是由重掺杂引入的晶体缺陷（深层供体最可能的模型是Se空位和Se位中的N的复合物）。所有这些都需要减少。氮掺杂ZnSe的外延和镜面对Se/Zn供应比的敏感性明显高于未掺杂ZnSe和n型ZnSe。这一事实使得上述3(3)所述的降低深层供体密度的尝试变得困难。具有相当光致发光性能的ZnSe层的电学性能取决于补偿比，为了获得更高的电导率，应通过选择适当的生长条件来降低补偿比。

1. The effective nitrogen species for epitaxial growth of p-type ZnSe are, in more effective order, (1) atomic nitrogen, (2) excited and ionized nitrogen molecules and (3) excited neutral nitrogen molecules. Further acceleration of ionized nitrogen can bring crystal defects.2. Dominant emission peaks in photoluminescence spectragenerally chages with increased nitrogen doping as (1) exciton emission bound to neutral nitrogen acceptor, (2) emission due to transition from conduction band to nitrogen acceptor level, (3) shallow donor to nitrogen acceptor pair emisson and (4) deepdonor to nitrogen acceptor pair emission.3. Compensating donors in nitrogen-doped ZnSe are (1) residualdonor impurities in source material (typically Cl in Se), (2) hydrogen in growth atmosphere and (3) crystal defects par-ticularly introduced by heavy doping (the most probalble model of deep donors is a complex of Se-vacancy and N in Se-site). All of them need to be reduced.4. Epitaxy and mirror surface of nitrogen-doped ZnSe is much more sensitive to Se/Zn supply ratio than undoped and n-type ZnSe. This fact makes difficult an attempt to reduce deep donor density indicated in the above 3 (3).5. Electrical properties of ZnSe layrs with comparable photoluminescent properties depend upon compensation ratio, which should be reduced for higher conductivity by selecting proper growth conditions.