InAlN材料表面态性质研究

Surface states of InAlN film grown by MOCVD

运用电流-电压(I-V),变频电容-电压(C-V)和原子力显微镜(AFM)技术研究In组分分别为15%,17%和21%的Ni/Au/-InAlN肖特基二极管InAlN样品表面态性质(表面态密度、时间常数和相对于InAlN导带底的能级位置).I-V和变频C-V方法测量得到的实验结果表明,随着In组分增加,肖特基势垒高度逐渐降低,表面态密度依次增加.变频C-V特性还表明,随着测试频率降低,C-V曲线有序地朝正电压方向移动,该趋势随着In组分的增加而变得更加明显,这可能归结于InAlN表面态的空穴发射.AFM表面形貌研究揭示InAlN表面粗糙度增加可能是表面态密度增加的主要原因.

The surface state properties （such as surface state density, time constant and level position related to the bottom of InAIN con- duction band） of Ni/Au/-InA1N Schottky barrier diodes with nearly lattice matched （InN = 18%） and tensilely （15%） or compressively （21%） strained InA1N barrier layer were evaluated, by using current-voltage （I-V）, frequency-dependent capacitance-voltage （C-V） measurements and atomic force microscope （AFM） images. It was found that, with increasing content of In the surface state density increased and the barrier height of the Schottky contacts decreased, respectively. The C-V curves shifted toward the positive bias val- ues with reducing measured frequencies, which became more apparent with increasing In content. It may be due to the hole emission from the surface states of Ni/Au/-InA1N Schottcky contacts. Atomic force microscope （AFM） images indicated that the InA1N surface became rougher with increasing In content, which may be the main reason for the increased surface state densities.