(1102)γ面蓝宝石生长的(1120)α面氮化镓研究

自发极化和压电极化是氮化镓制作光电器件没有解决的问题,对非极性GaN材料的研究解决了极化现象.采用低温AIN作为缓冲层,在(1102)γ面蓝宝石和(0001)с面蓝宝石上分别生长了(1120)非极性α面和(0001)极性с面GaN,用原子力显微镜和高分辨X射线衍射、光致发光谱比较了生长在γ面蓝宝石上的α面GaN和с面蓝宝石上的с面GaN,α面GaN材料质量和с面GaN相差较大,在α面GaN上发现了三角坑的表面形貌,这和传统的с面生长的极性GaN截然不同.对α面GaN的缺陷形成原因进行了讨论,并且确定了三角坑缺陷的晶向.     

fmax为30.8GHz的超薄Al2O3绝缘栅GaN MOS-HEMT器件

报道了一种利用原子层淀积(ALD)生长超薄(3.5nm)Al2O3为栅介质的高性能AlGaN/GaN金属氧化物半导体高电子迁移率晶体管(MOS-HEMT).新型AlGaN/GaN MOS-HEMT器件栅长1μm,栅宽120μm,栅压为+3.0V时最大饱和输出电流达到720mA/mm,最大跨导达到130mS/mm,开启电压保持在-5.0V,特征频率和最高振荡频率分别为10.1和30.8GHz.     

Surface morphology of [110] a-plane GaN growth by MOCVD on [1■02] r-plane sapphire

Nonpolar a-plane [110] GaN has been grown on r-plane [1■02] sapphire by MOCVD, and investigated by high resolution X-ray diffraction and atomic force microscopy. As opposed to the c-direction, this particular orientation is non-polar, and it avoids polarization charge, the associated screening charge and the consequent band bending. Both low-temperature GaN buffer and high-temperature AlN buffer are used for a-plane GaN growth on r-plane sapphire, and the triangular pits and pleat morphology come forth with different buffers, the possible reasons for which are discussed. The triangular and pleat direction are also investigated. A novel modulate buffer is used for a-plane GaN growth on r-plane sapphire, and with this technique, the crystal quality has been greatly improved.     

76.2mm Si基AlGaN/GaN HEMT

<正>南京电子器件研究所采用含有双AlGaN过渡层的材料结构在76.2 mm(3英寸)Si衬底上外延生长了厚度超过2μm的AlGaN/GaN HEMT材料(图1),材料表面光滑、无裂纹。通过外延材料结构和生长条     

MOCVD法生长InAlN材料及其微结构特性研究

利用MOCVD法,在7.62cm蓝宝石衬底上生长了InAlN薄膜及InAlN/GaN异质结材料。利用XRD、AFM、Hall等测试方法对材料的组分、表面形貌、电学性质等进行了分析,InAlN薄膜中In含量随生长温度的升高明显降低,材料表面为三维岛状结构;与AlGaN/GaN异质结材料相比,InAlN/GaN异质结的高温电子输运特性更好,773K下InAlN/GaN异质结的迁移率为130cm2/(v·s),明显高于AlGaN/GaN异质结的67cm2/(v·s)。     

Si基GaN材料寄生导电层的研究

通过对Si基GaN材料的电学性能进行测量分析,确认了该材料体系所特有的寄生导电层现象。研究了寄生导电层对Si基GaN高电子迁移率晶体管(HEMT)微波功率性能和击穿性能的不良影响。通过材料生长工艺的优化,降低了寄生导电层的导电性,获得了击穿电压超过320V的Si基GaN HEMT功率电子器件。     

立式MOCVD反应室感应加热温度场的有限元分析*

The temperature field in the vertical metalorganic chemical vapor deposition （MOCVD） reactor chamber used for the growth of GaN materials is studied using the finite element analysis method （FEM）. The effects of the relative position between the coils and the middle section of the susceptor, the radius of the coil, and the height of the susceptor on heating condition are analyzed. All simulation results indicate that the highest heating efficiency can be obtained under the conditions that the coil distributes symmetrically in the middle section of the susceptor and the ratio of the height of the susceptor to that of the coil is three-quarters. Furthermore, the heating efficiency is inversely proportional to the radius of the coil.     

fmax为30.8GHz的超薄Al2O3绝缘栅GaN MOS-HEMT器件

报道了一种利用原子层淀积(ALD)生长超薄(3.5nm)Al2O3为栅介质的高性能AlGaN/GaN金属氧化物半导体高电子迁移率晶体管(MOS-HEMT).新型AlGaN/GaN MOS-HEMT器件栅长1μm,栅宽120μm,栅压为 3.0V时最大饱和输出电流达到720mA/mm,最大跨导达到130mS/mm,开启电压保持在-5.0V,特征频率和最高振荡频率分别为10.1和30.8GHz.     

Si基GaN HEMT低温欧姆接触工艺研究

研究了在Si基GaN外延材料上实现低温欧姆接触的技术途径。研究了外延层的刻蚀深度、合金温度以及不同金属体系对接触特性的影响,发现外延层刻蚀深度的优化可显著改善欧姆接触特性。采用Ti/Al(10/200nm)金属,在外延层刻蚀深度为20nm以及合金温度550°C时,得到接近传统高温合金条件下的接触电阻,最小值达到0.76Ω.mm,同时实现的欧姆接触电极具有良好的形貌。该技术有望应用于高频、高功率GaN HEMT的工艺。     

含有Al组分阶变AlGaN过渡层的Si基AlGaN/GaN HEMT

采用一个AlN缓冲层和两个Al组分阶变的AlGaN过渡层作为中间层,在76.2mm Si衬底上外延生长出1.7μm厚无裂纹AlGaN/GaN异质结材料,利用原子力显微镜、X射线衍射、Hall效应测量和CV测量等手段对材料的结构特性和电学性能进行了表征。材料表面平整光滑,晶体质量和电学性能良好,2DEG面密度为1.12×1013cm-2,迁移率为1 208cm2/(V.s)。由该材料研制的栅长为1μm的AlGaN/GaN HEMT器件,电流增益截止频率fT达到10.4GHz,这些结果表明组分阶变AlGaN过渡层技术可用于实现高性能Si基GaN HEMT。