Dependence of mobility on density of gap states in organics by GAMEaS-gate modulated activation energy spectroscopy

We develop a broadly applicable transport-based technique, gate modulated activation energy spectroscopy (GAMEaS), for determining the density of states (DOS) in an energy gap. GAMEaS is applied to field-effect transistors (FETs) made from different single crystal oligomer semiconductors. We find that there are two distinct types of band tails, deep and shallow, depending on the crystallization process. The exponential band tails of the localized DOS are characterized by their slope with the highest mobility FETs having a value of 29 eV−1 close to 1/kBT at 300 K.

[1]  A. P. Ramirez,et al.  Low-temperature field effect in a crystalline organic material , 2004, cond-mat/0405077.

[2]  Oana D. Jurchescu,et al.  Effect of impurities on the mobility of single crystal pentacene , 2004, cond-mat/0404130.

[3]  D. Lang,et al.  Bias-dependent generation and quenching of defects in pentacene. , 2003, Physical review letters.

[4]  D. Lang,et al.  Amorphouslike density of gap states in single-crystal pentacene. , 2003, Physical review letters.

[5]  Arthur P. Ramirez,et al.  Free-standing tetracene single crystal field effect transistor , 2003 .

[6]  K. Pernstich,et al.  Field-induced charge transport at the surface of pentacene single crystals: A method to study charge dynamics of two-dimensional electron systems in organic crystals , 2003, cond-mat/0306206.

[7]  S. Sysoev,et al.  Single-crystal organic field effect transistors with the hole mobility ∼8 cm2/V s , 2003, cond-mat/0306192.

[8]  D. Lang,et al.  Field-effect transistor on pentacene single crystal , 2003, cond-mat/0305402.

[9]  G. Horowitz,et al.  Tunneling Current in Polycrystalline Organic Thin‐Film Transistors , 2003 .

[10]  Robert A. Street,et al.  Carrier transport and density of state distributions in pentacene transistors , 2002 .

[11]  V. Podzorov,et al.  Field-effect transistors on rubrene single crystals with parylene gate insulator , 2002, cond-mat/0210555.

[12]  S. Nespurek,et al.  Temperature dependent space‐charge‐limited currents in amorphous and disordered semiconductors , 1996 .

[13]  Gilles Horowitz,et al.  Temperature Dependence of the Field-Effect Mobility of Sexithiophene. Determination of the Density of Traps , 1995 .

[14]  W. Warta,et al.  Hot holes in naphthalene: High, electric-field-dependent mobilities. , 1985, Physical review. B, Condensed matter.

[15]  D. Dunstan.  Evidence for a common origin of the Urbach tails in amorphous and crystalline semiconductors , 1982 .

[16]  H. Grubin.  The physics of semiconductor devices , 1979, IEEE Journal of Quantum Electronics.

[17]  Digby F. Williams,et al.  Temperature dependence and anisotropy of charge carrier mobilities in durene , 1977 .

[18]  C. Sah,et al.  Effects of diffusion current on characteristics of metal-oxide (insulator)-semiconductor transistors☆ , 1966 .